port: don't force libc++, fix system.c on clang16+

Makefile.port

@@ -168,10 +168,6 @@ else # assume *nix
     # TODO: detect soft/hardfloat abi
     TOOLCHAIN ?= arm-linux-gnueabihf-
   endif
-  # on clang link libc++
-  ifneq (,$(findstring clang,$(CC))$(findstring clang,$(CXX)))
-    TARGET_LDFLAGS += -lc++
-  endif
 endif
 
 # On x86_64 gcc add -m32 to CFLAGS if building a 32-bit executable.

port/src/system.c

@@ -1,3 +1,7 @@
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE 1
+#endif
+
 #include <stdlib.h>
 #include <stdarg.h>
 #include <stdio.h>
@@ -28,10 +32,6 @@ __attribute__((dllexport)) u32 AmdPowerXpressRequestHighPerformance = 1;
 
 #else
 
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE 1
-#endif
-
 #include <unistd.h>
 
 // figure out how to yield