Revert "[clang][X86] Add __cpuidex function to cpuid.h"

This reverts commit 2df77ac.

This has been causing some issues with some windows builds as
_MSC_EXTENSIONS isn't defined when only -fms-extensions is set, but the
builtin that conflicts with __cpuidex is. This was also causing problems
as it exposed some latent issues with how auxiliary triples are handled
in clang.

Differential Revision: https://reviews.llvm.org/D157115

(cherry picked from commit f3baf63)

Author: boomanaiden154

clang/lib/Headers/cpuid.h

@@ -328,14 +328,4 @@ static __inline int __get_cpuid_count (unsigned int __leaf,
     return 1;
 }
 
-// If MS extensions are enabled, __cpuidex is defined as a builtin which will
-// conflict with the __cpuidex definition below.
-#ifndef _MSC_EXTENSIONS
-static __inline void __cpuidex (int __cpu_info[4], int __leaf, int __subleaf)
-{
-  __cpuid_count(__leaf, __subleaf, __cpu_info[0], __cpu_info[1], __cpu_info[2],
-                __cpu_info[3]);
-}
-#endif
-
 #endif /* __CPUID_H */

clang/test/Headers/__cpuidex_conflict.c

@@ -6,19 +6,14 @@
 
 // CHECK-64: {{.*}} call { i32, i32, i32, i32 } asm "  xchgq  %rbx,${1:q}\0A cpuid\0A xchgq %rbx,${1:q}", "={ax},=r,={cx},={dx},0,~{dirflag},~{fpsr},~{flags}"(i32 %{{[a-z0-9]+}})
 // CHECK-64: {{.*}} call { i32, i32, i32, i32 } asm "  xchgq  %rbx,${1:q}\0A  cpuid\0A  xchgq  %rbx,${1:q}", "={ax},=r,={cx},={dx},0,2,~{dirflag},~{fpsr},~{flags}"(i32 %{{[a-z0-9]+}}, i32 %{{[a-z0-9]+}})
-// CHECK-64: {{.*}} call { i32, i32, i32, i32 } asm "  xchgq  %rbx,${1:q}\0A  cpuid\0A  xchgq  %rbx,${1:q}", "={ax},=r,={cx},={dx},0,2,~{dirflag},~{fpsr},~{flags}"(i32 %{{[a-z0-9]+}}, i32 %{{[a-z0-9]+}})
 
 // CHECK-32: {{.*}} call { i32, i32, i32, i32 } asm "cpuid", "={ax},={bx},={cx},={dx},0,~{dirflag},~{fpsr},~{flags}"(i32 %{{[a-z0-9]+}})
 // CHECK-32: {{.*}} call { i32, i32, i32, i32 } asm "cpuid", "={ax},={bx},={cx},={dx},0,2,~{dirflag},~{fpsr},~{flags}"(i32 %{{[a-z0-9]+}}, i32 %{{[a-z0-9]+}})
-// CHECK-32: {{.*}} call { i32, i32, i32, i32 } asm "cpuid", "={ax},={bx},={cx},={dx},0,2,~{dirflag},~{fpsr},~{flags}"(i32 %{{[a-z0-9]+}}, i32 %{{[a-z0-9]+}})
 
 unsigned eax0, ebx0, ecx0, edx0;
 unsigned eax1, ebx1, ecx1, edx1;
 
-int cpuid_info[4];
-
 void test_cpuid(unsigned level, unsigned count) {
   __cpuid(level, eax1, ebx1, ecx1, edx1);
   __cpuid_count(level, count, eax0, ebx0, ecx0, edx0);
-  __cpuidex(cpuid_info, level, count);
 }