pkg/csource: remove C23 embed built-in defines

The new C23 embed built-in defines cause build errors in executor with
GCC 15.

<stdin>:3:9: error: ‘__STDC_EMBED_NOT_FOUND__’ redefined [-Werror]
<built-in>: note: this is the location of the previous definition
<stdin>:4:9: error: ‘__STDC_EMBED_FOUND__’ redefined [-Werror]
<built-in>: note: this is the location of the previous definition
<stdin>:5:9: error: ‘__STDC_EMBED_EMPTY__’ redefined [-Werror]
<built-in>: note: this is the location of the previous definition

Signed-off-by: Alexander Egorenkov <eaibmz@gmail.com>

Author: eaibmz

pkg/csource/common.go

@@ -132,10 +132,13 @@ func commonDefines(p *prog.Prog, opts Options) map[string]bool {
 
 func removeSystemDefines(src []byte, defines []string) ([]byte, error) {
 	remove := map[string]string{
-		"__STDC__":        "1",
-		"__STDC_HOSTED__": "1",
-		"__STDC_UTF_16__": "1",
-		"__STDC_UTF_32__": "1",
+		"__STDC__":                 "1",
+		"__STDC_HOSTED__":          "1",
+		"__STDC_UTF_16__":          "1",
+		"__STDC_UTF_32__":          "1",
+		"__STDC_EMBED_NOT_FOUND__": "0",
+		"__STDC_EMBED_FOUND__":     "1",
+		"__STDC_EMBED_EMPTY__":     "2",
 	}
 	for _, def := range defines {
 		eq := strings.IndexByte(def, '=')