cgo: add support for the -T flag

This adds support for specifying linker scripts in LDFLAGS. I looked a
bit into whether it allows arbitrary code execution but I couldn't find
any sign of that.

Author: aykevl

cgo/cgo.go

@@ -447,11 +447,11 @@ func makePathsAbsolute(args []string, packagePath string) {
 				args[i] = filepath.Join(packagePath, arg)
 			}
 		}
-		if arg == "-I" || arg == "-L" {
+		if arg == "-I" || arg == "-L" || arg == "-T" {
 			nextIsPath = true
 			continue
 		}
-		if strings.HasPrefix(arg, "-I") || strings.HasPrefix(arg, "-L") {
+		if strings.HasPrefix(arg, "-I") || strings.HasPrefix(arg, "-L") || strings.HasPrefix(arg, "-T") {
 			path := arg[2:]
 			if !filepath.IsAbs(path) {
 				args[i] = arg[:2] + filepath.Join(packagePath, path)

cgo/security.go

@@ -140,6 +140,7 @@ var validLinkerFlags = []*regexp.Regexp{
 	re(`-F([^@\-].*)`),
 	re(`-l([^@\-].*)`),
 	re(`-L([^@\-].*)`),
+	re(`-T([^@\-].*)`),
 	re(`-O`),
 	re(`-O([^@\-].*)`),
 	re(`-f(no-)?(pic|PIC|pie|PIE)`),
@@ -209,6 +210,7 @@ var validLinkerFlagsWithNextArg = []string{
 	"-F",
 	"-l",
 	"-L",
+	"-T",
 	"-framework",
 	"-isysroot",
 	"--sysroot",