[X86] Add missing CET intrinsics support

[FreddyYe]

Summary

These two intrinsics are documented o SDM and intrinsic guide.

[pengfei]

Checked we won't raise uninitialized warning, so LGTM.

clang/lib/Headers/cetintrin.h

static __inline__ void __DEFAULT_FN_ATTRS _inc_ssp(unsigned int __a) {
   __builtin_ia32_incsspd((int)__a);
 }
 #endif /* __x86_64__ */
 
 static __inline__ unsigned int __DEFAULT_FN_ATTRS _rdsspd(unsigned int __a) {
   return __builtin_ia32_rdsspd(__a);
 }
 
+static __inline__ unsigned int __DEFAULT_FN_ATTRS _rdsspd_i32() {
+  unsigned int t;
+  return __builtin_ia32_rdsspd(t);
+}
+
 #ifdef __x86_64__
 static __inline__ unsigned long long __DEFAULT_FN_ATTRS _rdsspq(unsigned long long __a) {
   return __builtin_ia32_rdsspq(__a);
 }
+
+static __inline__ unsigned long long __DEFAULT_FN_ATTRS _rdsspq_i64() {
+  unsigned long long t;
+  return __builtin_ia32_rdsspq(t);
+}
 #endif /* __x86_64__ */
 
 #ifdef __x86_64__
 static __inline__ unsigned long long __DEFAULT_FN_ATTRS _get_ssp(void) {
   return __builtin_ia32_rdsspq(0);
 }
 #else /* __x86_64__ */
 static __inline__ unsigned int __DEFAULT_FN_ATTRS _get_ssp(void) {

clang/test/CodeGen/X86/cetintrin.c

 #endif
 
 unsigned int test_rdsspd(unsigned int a) {
   // CHECK-LABEL: @test_rdsspd
   // CHECK:       call i32 @llvm.x86.rdsspd(i32 %{{[a-z0-9.]+}})
   return _rdsspd(a);
 }
 
+unsigned int test_rdsspd_i32() {
+  // CHECK-LABEL: @test_rdsspd_i32
+  // CHECK:       call i32 @llvm.x86.rdsspd(i32 %{{[a-z0-9.]+}})
+  return _rdsspd_i32();
+}
+
 #ifdef __x86_64__
 unsigned long long test_rdsspq(unsigned long long a) {
   // X86_64-LABEL: @test_rdsspq
   // X86_64:       call i64 @llvm.x86.rdsspq(i64 %{{[a-z0-9.]+}})
   return _rdsspq(a);
 }
 
+unsigned long long test_rdsspq_i64() {
+  // X86_64-LABEL: @test_rdsspq_i64
+  // X86_64:       call i64 @llvm.x86.rdsspq(i64 %{{[a-z0-9.]+}})
+  return _rdsspq_i64();
+}
+
 unsigned long long test_get_ssp(void) {
   // X86_64-LABEL: @test_get_ssp
   // X86_64:       call i64 @llvm.x86.rdsspq(i64 0)
   return _get_ssp();
 }
 
 #else