Fix a couple issues for Xcode projects (#513)

* Link separate JSystem libraries due to control.cpp

This allows the Xcode generator to work, otherwise
it breaks on the duplicate control.o files within
the game_debug library.

* Fix __memcpy define on GCC

* Try LINK_GROUP:RESCAN for GNU ld

* Combine dusk/game_base/game_debug targets

* Fix compile defs syntax

src/dusk/extras.c

@@ -3,6 +3,27 @@
 #include <string.h>
 #include <stdint.h>
 
+#ifdef _MSC_VER
+#include <intrin.h>
+#endif
+
+void __dcbz(void* addr, int offset) {
+    // Gekko cache lines are 32 bytes.
+    // dcbz usually requires addr to be 32-byte aligned.
+    memset((char*)addr + offset, 0, 32);
+}
+
+int __cntlzw(unsigned int val) {
+    if (val == 0) return 32; // PowerPC returns 32 if the input is 0
+#ifdef _MSC_VER
+    unsigned long idx;
+    _BitScanReverse(&idx, val);
+    return 31 - (int)idx;
+#else
+    return __builtin_clz(val);
+#endif
+}
+
 #ifndef _MSC_VER
 int stricmp(const char* str1, const char* str2) {
 	char a_var;
@@ -48,11 +69,6 @@ int strnicmp(const char* str1, const char* str2, int n) {
 }
 #endif
 
-
-void *_memcpy(void* dest, void const* src, int n) {
-    return memcpy(dest, src, n);
-}
-
 void DCZeroRange(void* addr, uint32_t nBytes) {
 #if defined(_MSC_VER) || TARGET_ANDROID
     memset(addr, 0, nBytes);

src/dusk/extras.cpp

@@ -1,27 +0,0 @@
-// C++ Mangled version of extras.c
-#include <cstring>
-#include <cstdint>
-#ifdef _MSC_VER
-#include <intrin.h>
-#endif
-
-void *__memcpy(void* dest, void const* src, int n) {
-    return memcpy(dest, src, n);
-}
-
-void __dcbz(void* addr, int offset) {
-    // Gekko cache lines are 32 bytes.
-    // dcbz usually requires addr to be 32-byte aligned.
-    memset((char*)addr + offset, 0, 32); 
-}
-
-int __cntlzw(unsigned int val) {
-    if (val == 0) return 32; // PowerPC returns 32 if the input is 0
-#ifdef _MSC_VER
-    unsigned long idx;
-    _BitScanReverse(&idx, val);
-    return 31 - (int)idx;
-#else
-    return __builtin_clz(val);
-#endif
-}