go: only enable PIE by default when building for GOARCH matching target

We rely on teaching go to use the correct ELF interpreter
for PIE in a way that can't work for packages that 
go off and do their own GOARCH=something cross builds
without touching nixpkgs cross machinery,
so update the default pie patch to bake targetPlatform's
GOARCH and only activate for it.

tailscale works as a testcase for this as it cross compiles
many arches in tstest/archtest/qemu_test.go

pkgs/development/compilers/go/1.24.nix

@@ -65,7 +65,9 @@ stdenv.mkDerivation (finalAttrs: {
     ./remove-tools-1.11.patch
     ./go_no_vendor_checks-1.23.patch
     ./go-env-go_ldso.patch
-    ./go-default-pie.patch
+    (replaceVars ./go-default-pie.patch {
+      inherit (stdenv.targetPlatform.go) GOARCH;
+    })
   ];
 
   inherit (stdenv.targetPlatform.go) GOOS GOARCH GOARM;

pkgs/development/compilers/go/1.25.nix

@@ -75,7 +75,9 @@ stdenv.mkDerivation (finalAttrs: {
     ./remove-tools-1.11.patch
     ./go_no_vendor_checks-1.23.patch
     ./go-env-go_ldso.patch
-    ./go-default-pie.patch
+    (replaceVars ./go-default-pie.patch {
+      inherit (stdenv.targetPlatform.go) GOARCH;
+    })
   ];
 
   inherit (stdenv.targetPlatform.go) GOOS GOARCH GOARM;

pkgs/development/compilers/go/go-default-pie.patch

@@ -7,7 +7,7 @@ index f9706a6988..abac42d550 100644
  		return true
  	}
 -	return false
-+	return BuildModeSupported("gc", "pie", goos, goarch)
++	return goarch == "@GOARCH@" && BuildModeSupported("gc", "pie", goos, goarch)
  }
  
  // ExecutableHasDWARF reports whether the linked executable includes DWARF