remove universal build flags from makefile

removed -arch i386 from makefile to build specifically on x86_64 to fix:

/sw/include/curl/curlrules.h:143:6: error: '__curl_rule_01__' declared
as an array
with a negative size
[CurlchkszEQ(long, CURL_SIZEOF_LONG)];
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/sw/include/curl/curlrules.h:132:27: note: expanded from macro
'CurlchkszEQ'
#define CurlchkszEQ(t, s) sizeof(t) == s ? 1 : -1

Makefile

@@ -119,7 +119,7 @@ ifeq ($(UNAME),Darwin)
       SOURCES += $(SOURCES_iphoneos)
 # Starting with Xcode 4.0, the PowerPC compiler is not installed by default
       ifeq ($(wildcard /usr/llvm-gcc-4.2/libexec/gcc/powerpc*), )
-        FAT_FLAGS = -arch i386 -arch x86_64 -mmacosx-version-min=10.5
+        FAT_FLAGS = -arch x86_64 -mmacosx-version-min=10.5
       else
         FAT_FLAGS = -arch ppc -arch i386 -arch x86_64 -mmacosx-version-min=10.4
       endif