Fixed cpuid assembly to work on PIC code

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%404333

src/cpuinfo/SDL_cpuinfo.c

@@ -156,8 +156,12 @@ done:
 
 #if defined(__GNUC__) && (defined(i386) || defined(__x86_64__))
 #define cpuid(func, a, b, c, d) \
-    __asm__ __volatile__ ("cpuid": \
-    "=a" (a), "=b" (b), "=c" (c), "=d" (d) : "a" (func))
+    __asm__ __volatile__ ( \
+"        pushl %%ebx        \n" \
+"        cpuid              \n" \
+"        movl %%ebx, %%esi  \n" \
+"        popl %%ebx         \n" : \
+            "=a" (a), "=S" (b), "=c" (c), "=d" (d) : "a" (func))
 #elif (defined(_MSC_VER) && defined(_M_IX86)) || defined(__WATCOMC__)
 #define cpuid(func, a, b, c, d) \
     __asm { \