compiler: use full paths for debug info files if relative can't be constructed
Firstly introduced in 9871dc8f5a. It's OK
if relative path can't be constructed e.g. for interop dependencies. Otherwice
leads to failing tests on Windows with the following error:
```
2022-02-09T09:39:31.3307626Z panic: Rel: can't make D:\a\neo-go\neo-go\pkg\interop\neogointernal\syscall.go relative to C:\Users\RUNNER~1\AppData\Local\Temp\TestContractInitAndCompile1998984267\001\testcontract [recovered]
2022-02-09T09:39:31.3308830Z panic: Rel: can't make D:\a\neo-go\neo-go\pkg\interop\neogointernal\syscall.go relative to C:\Users\RUNNER~1\AppData\Local\Temp\TestContractInitAndCompile1998984267\001\testcontract
2022-02-09T09:39:31.3309285Z
2022-02-09T09:39:31.3309390Z goroutine 302 [running]:
2022-02-09T09:39:31.3309725Z testing.tRunner.func1.2({0x14dbfe0, 0xc00051bdb0})
2022-02-09T09:39:31.3310187Z C:/hostedtoolcache/windows/go/1.17.6/x64/src/testing/testing.go:1209 +0x36c
2022-02-09T09:39:31.3310538Z testing.tRunner.func1()
2022-02-09T09:39:31.3310937Z C:/hostedtoolcache/windows/go/1.17.6/x64/src/testing/testing.go:1212 +0x3b6
2022-02-09T09:39:31.3311285Z panic({0x14dbfe0, 0xc00051bdb0})
2022-02-09T09:39:31.3311689Z C:/hostedtoolcache/windows/go/1.17.6/x64/src/runtime/panic.go:1047 +0x266
2022-02-09T09:39:31.3312319Z github.com/nspcc-dev/neo-go/pkg/compiler.(*codegen).fillDocumentInfo.func1(0xc0002d0b40)
2022-02-09T09:39:31.3312885Z D:/a/neo-go/neo-go/pkg/compiler/analysis.go:240 +0x34d
2022-02-09T09:39:31.3313397Z go/token.(*FileSet).Iterate(0xc0000a69c0, 0xc0004898b0)
2022-02-09T09:39:31.3313839Z C:/hostedtoolcache/windows/go/1.17.6/x64/src/go/token/position.go:463 +0xde
2022-02-09T09:39:31.3314404Z github.com/nspcc-dev/neo-go/pkg/compiler.(*codegen).fillDocumentInfo(0xc0002e4d20)
2022-02-09T09:39:31.3314947Z D:/a/neo-go/neo-go/pkg/compiler/analysis.go:236 +0x97
2022-02-09T09:39:31.3315530Z github.com/nspcc-dev/neo-go/pkg/compiler.(*codegen).compile(0xc0002e4d20, 0xc00009a690, 0xc000101540)
2022-02-09T09:39:31.3316064Z D:/a/neo-go/neo-go/pkg/compiler/codegen.go:2088 +0x192
2022-02-09T09:39:31.3316563Z github.com/nspcc-dev/neo-go/pkg/compiler.codeGen(0xc00009a690)
2022-02-09T09:39:31.3317066Z D:/a/neo-go/neo-go/pkg/compiler/codegen.go:2167 +0x7cd
2022-02-09T09:39:31.3317679Z github.com/nspcc-dev/neo-go/pkg/compiler.CompileWithOptions({0xc0000435e0, 0x62}, {0x0, 0x0}, 0xc0004bcf70)
2022-02-09T09:39:31.3318233Z D:/a/neo-go/neo-go/pkg/compiler/compiler.go:225 +0xde
2022-02-09T09:39:31.3318804Z github.com/nspcc-dev/neo-go/pkg/compiler.CompileAndSave({0xc0000435e0, 0x62}, 0xc0004bcf70)
2022-02-09T09:39:31.3319353Z D:/a/neo-go/neo-go/pkg/compiler/compiler.go:241 +0x3a5
2022-02-09T09:39:31.3319889Z github.com/nspcc-dev/neo-go/cli/smartcontract.contractCompile(0xc0004e42c0)
2022-02-09T09:39:31.3320456Z D:/a/neo-go/neo-go/cli/smartcontract/smart_contract.go:520 +0xc2d
2022-02-09T09:39:31.3320873Z github.com/urfave/cli.HandleAction({0x14b6fa0, 0x17b8d60}, 0x7)
2022-02-09T09:39:31.3321344Z C:/Users/runneradmin/go/pkg/mod/github.com/urfave/cli@v1.22.5/app.go:524 +0xf4
2022-02-09T09:39:31.3321931Z github.com/urfave/cli.Command.Run({{0x16460d2, 0x7}, {0x0, 0x0}, {0x0, 0x0, 0x0}, {0x166fe9e, 0x27}, {0x0, ...}, ...}, ...)
2022-02-09T09:39:31.3322443Z C:/Users/runneradmin/go/pkg/mod/github.com/urfave/cli@v1.22.5/command.go:173 +0xc09
2022-02-09T09:39:31.3322894Z github.com/urfave/cli.(*App).RunAsSubcommand(0xc0000b7340, 0xc0004e4000)
2022-02-09T09:39:31.3323375Z C:/Users/runneradmin/go/pkg/mod/github.com/urfave/cli@v1.22.5/app.go:405 +0x106c
2022-02-09T09:39:31.3323852Z github.com/urfave/cli.Command.startApp({{0x1647536, 0x8}, {0x0, 0x0}, {0x0, 0x0, 0x0}, {0x1671070, 0x28}, {0x0, ...}, ...}, ...)
2022-02-09T09:39:31.3324365Z C:/Users/runneradmin/go/pkg/mod/github.com/urfave/cli@v1.22.5/command.go:372 +0x108c
2022-02-09T09:39:31.3324838Z github.com/urfave/cli.Command.Run({{0x1647536, 0x8}, {0x0, 0x0}, {0x0, 0x0, 0x0}, {0x1671070, 0x28}, {0x0, ...}, ...}, ...)
2022-02-09T09:39:31.3325327Z C:/Users/runneradmin/go/pkg/mod/github.com/urfave/cli@v1.22.5/command.go:102 +0xe8c
2022-02-09T09:39:31.3325744Z github.com/urfave/cli.(*App).Run(0xc000323880, {0xc0004237a0, 0xb, 0x12})
2022-02-09T09:39:31.3326198Z C:/Users/runneradmin/go/pkg/mod/github.com/urfave/cli@v1.22.5/app.go:277 +0xa8c
2022-02-09T09:39:31.3326770Z github.com/nspcc-dev/neo-go/cli.(*executor).run(0xc0000709c0, {0xc0004237a0, 0xb, 0x12})
2022-02-09T09:39:31.3327275Z D:/a/neo-go/neo-go/cli/executor_test.go:273 +0x3a5
2022-02-09T09:39:31.3327812Z github.com/nspcc-dev/neo-go/cli.(*executor).Run(0x14aa020, 0xc000493950, {0xc0004237a0, 0xb, 0x12})
2022-02-09T09:39:31.3328324Z D:/a/neo-go/neo-go/cli/executor_test.go:263 +0x10f
2022-02-09T09:39:31.3328844Z github.com/nspcc-dev/neo-go/cli.TestContractInitAndCompile(0xc0001d69c0)
2022-02-09T09:39:31.3329377Z D:/a/neo-go/neo-go/cli/contract_test.go:155 +0x147f
2022-02-09T09:39:31.3329694Z testing.tRunner(0xc0001d69c0, 0x17b8be8)
2022-02-09T09:39:31.3330123Z C:/hostedtoolcache/windows/go/1.17.6/x64/src/testing/testing.go:1259 +0x230
2022-02-09T09:39:31.3330470Z created by testing.(*T).Run
2022-02-09T09:39:31.3330862Z C:/hostedtoolcache/windows/go/1.17.6/x64/src/testing/testing.go:1306 +0x727
2022-02-09T09:39:31.3331325Z FAIL github.com/nspcc-dev/neo-go/cli 5.552s
```
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