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

@@ -136,6 +136,9 @@ func removeSystemDefines(src []byte, defines []string) ([]byte, error) {
 		"__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, '=')