Fix stdint.h intptr_t/uintptr_t for x86_64/x32

Patch is required in NDK headers as well to be able to build multilib
GCC with libgomp support.
It's here: https://android-review.googlesource.com/#/c/62982

Change-Id: I2bec25d8cbca0e5ef1a0857008ececd92f4911be
Signed-off-by: Pavel Chupin <pavel.v.chupin@intel.com>

libc/include/stdint.h

@@ -191,8 +191,13 @@ typedef uint64_t      uint_fast64_t;
  * intptr_t & uintptr_t
  */
 
+#ifdef __LP64__
+typedef long           intptr_t;
+typedef unsigned long  uintptr_t;
+#else
 typedef int           intptr_t;
 typedef unsigned int  uintptr_t;
+#endif
 
 #ifdef __STDINT_LIMITS
 #  define INTPTR_MIN    INT32_MIN