Zero ecx with a mov instruction

PGI assembler does not like the initialization in the constraints.

common_x86_64.h

@@ -129,12 +129,13 @@ static __inline void cpuid(int op, int *eax, int *ebx, int *ecx, int *edx){
   *ecx=cpuinfo[2];
   *edx=cpuinfo[3];
 #else
-        __asm__ __volatile__("cpuid"
+        __asm__ __volatile__("mov %%ecx, 0;"
+			     "cpuid"
 			     : "=a" (*eax),
 			     "=b" (*ebx),
 			     "=c" (*ecx),
 			     "=d" (*edx)
-			     : "0" (op), "c"(0));
+			     : "0" (op));
 #endif
 }