compiler: support basic inlining

pkg/compiler/testdata/inline/inline.go

@@ -0,0 +1,32 @@
+package inline
+
+import (
+	"github.com/nspcc-dev/neo-go/pkg/compiler/testdata/inline/a"
+	"github.com/nspcc-dev/neo-go/pkg/compiler/testdata/inline/b"
+)
+
+func NoArgsNoReturn() {}
+func NoArgsReturn1() int {
+	return 1
+}
+func Sum(a, b int) int {
+	return a + b
+}
+func sum(x, y int) int {
+	return x + y
+}
+func SumSquared(a, b int) int {
+	return sum(a, b) * (a + b)
+}
+
+var A = 1
+
+func GetSumSameName() int {
+	return a.GetA() + b.GetA() + A
+}
+
+func DropInsideInline() int {
+	sum(1, 2)
+	sum(3, 4)
+	return 7
+}