reenable aix builds

changelog/unreleased/pull-4365

@@ -1,6 +0,0 @@
-Change: Building restic on AIX is temporarily unsupported
-
-As the current version of the library used for the Azure backend does not
-compile on AIX, there are currently no restic builds available for AIX.
-
-https://github.com/restic/restic/pull/4365

helpers/build-release-binaries/main.go

@@ -239,6 +239,7 @@ func buildTargets(sourceDir, outputDir string, targets map[string][]string) {
 }
 
 var defaultBuildTargets = map[string][]string{
+	"aix":     {"ppc64"},
 	"darwin":  {"amd64", "arm64"},
 	"freebsd": {"386", "amd64", "arm"},
 	"linux":   {"386", "amd64", "arm", "arm64", "ppc64le", "mips", "mipsle", "mips64", "mips64le", "riscv64", "s390x"},