cmd/go: permit .tbd files as a linker flag

A .tbd file is a macOS text-based stub library and is a valid input to
the macOS linker. This change adds .tbd to the allow-list for acceptable
linker flags.

Fixes golang/go#44263

src/cmd/go/internal/work/security.go

@@ -208,7 +208,7 @@ var validLinkerFlags = []*lazyregexp.Regexp{
 	re(`-Wl,-z,(no)?execstack`),
 	re(`-Wl,-z,relro`),
 
-	re(`[a-zA-Z0-9_/].*\.(a|o|obj|dll|dylib|so)`), // direct linker inputs: x.o or libfoo.so (but not -foo.o or @foo.o)
+	re(`[a-zA-Z0-9_/].*\.(a|o|obj|dll|dylib|so|tbd)`), // direct linker inputs: x.o or libfoo.so (but not -foo.o or @foo.o)
 	re(`\./.*\.(a|o|obj|dll|dylib|so)`),
 }
 

src/cmd/go/internal/work/security_test.go

@@ -164,6 +164,7 @@ var goodLinkerFlags = [][]string{
 	{"-Wl,-framework", "-Wl,Chocolate"},
 	{"-Wl,-framework,Chocolate"},
 	{"-Wl,-unresolved-symbols=ignore-all"},
+	{"libcgotbdtest.tbd"},
 }
 
 var badLinkerFlags = [][]string{