Better build compatibility

Makefile.libretro

@@ -2,13 +2,17 @@ STATIC_LINKING=0
 
 ifeq ($(platform),)
 platform = unix
-ifeq ($(shell uname -a),)
+ifeq ($(shell uname -s),)
    platform = win
-else ifneq ($(findstring MINGW,$(shell uname -a)),)
+else ifneq ($(findstring MINGW,$(shell uname -s)),)
    platform = win
-else ifneq ($(findstring Darwin,$(shell uname -a)),)
+else ifneq ($(findstring Darwin,$(shell uname -s)),)
    platform = osx
-else ifneq ($(findstring win,$(shell uname -a)),)
+		arch = intel
+		ifeq ($(shell uname -p),powerpc)
+			arch = ppc
+		endif
+else ifneq ($(findstring win,$(shell uname -s)),)
    platform = win
 endif
 endif
@@ -21,9 +25,9 @@ ifeq ($(shell uname -a),)
 else ifneq ($(findstring Darwin,$(shell uname -a)),)
 	system_platform = osx
 	arch = intel
-ifeq ($(shell uname -p),powerpc)
-	arch = ppc
-endif
+	ifeq ($(shell uname -p),powerpc)
+		arch = ppc
+	endif
 else ifneq ($(findstring MINGW,$(shell uname -a)),)
 	system_platform = win
 endif
@@ -41,14 +45,6 @@ LIBS := -lm
 endif
 fpic=
 
-ifeq ($(ARCHFLAGS),)
-ifeq ($(archs),ppc)
-   ARCHFLAGS = -arch ppc -arch ppc64
-else
-   ARCHFLAGS = -arch i386 -arch x86_64
-endif
-endif
-
 ifeq ($(STATIC_LINKING),1)
 	EXT=a