[builtins] Mark int_lib.h builtins as static (#69305)

Mark the following symbols as `static` to prevent duplicate definitions:

`__builtin_ctz`
`__builtin_clz`
`__builtin_clzll`
`__builtin_sadd_overflow`

>Without these then all of these functions show up in all object files
which include int_lib.h on Windows. This'll help prevent duplicate
symbols by ensuring they're not exported.

See:

rust-lang/compiler-builtins#167
https://reviews.llvm.org/D34599

Author: trevyn

compiler-rt/lib/builtins/int_lib.h

@@ -119,29 +119,29 @@ COMPILER_RT_ABI tu_int __udivmodti4(tu_int a, tu_int b, tu_int *rem);
 #if defined(_MSC_VER) && !defined(__clang__)
 #include <intrin.h>
 
-int __inline __builtin_ctz(uint32_t value) {
+static int __inline __builtin_ctz(uint32_t value) {
   unsigned long trailing_zero = 0;
   if (_BitScanForward(&trailing_zero, value))
     return trailing_zero;
   return 32;
 }
 
-int __inline __builtin_clz(uint32_t value) {
+static int __inline __builtin_clz(uint32_t value) {
   unsigned long leading_zero = 0;
   if (_BitScanReverse(&leading_zero, value))
     return 31 - leading_zero;
   return 32;
 }
 
 #if defined(_M_ARM) || defined(_M_X64)
-int __inline __builtin_clzll(uint64_t value) {
+static int __inline __builtin_clzll(uint64_t value) {
   unsigned long leading_zero = 0;
   if (_BitScanReverse64(&leading_zero, value))
     return 63 - leading_zero;
   return 64;
 }
 #else
-int __inline __builtin_clzll(uint64_t value) {
+static int __inline __builtin_clzll(uint64_t value) {
   if (value == 0)
     return 64;
   uint32_t msh = (uint32_t)(value >> 32);
@@ -154,7 +154,7 @@ int __inline __builtin_clzll(uint64_t value) {
 
 #define __builtin_clzl __builtin_clzll
 
-bool __inline __builtin_sadd_overflow(int x, int y, int *result) {
+static bool __inline __builtin_sadd_overflow(int x, int y, int *result) {
   if ((x < 0) != (y < 0)) {
     *result = x + y;
     return false;