Switch to '__asm__' over 'asm' (#41)

* Use more compliant '__asm__' over 'asm'

* Use more compliant '__asm__' over 'asm'

Author: MichaelChirico

src/base64.c

@@ -25,7 +25,7 @@ volatile uint32_t mbedtls_ct_zero = 0;
 
 static inline uint32_t mbedtls_ct_compiler_opaque(uint32_t x) {
 #if defined(MBEDTLS_CT_ASM)
-  asm volatile ("" : [x] "+r" (x) :);
+  __asm__ volatile ("" : [x] "+r" (x) :);
   return x;
 #else
   return x ^ mbedtls_ct_zero;

src/sha3.c

@@ -209,7 +209,7 @@ static void * (*const volatile secure_memset)(void *, int, size_t) = memset;
 inline void sb_clear_buffer(void *buf, const size_t sz) {
 #ifdef MBEDTLS_CT_ASM
   memset(buf, 0, sz);
-  asm volatile ("" ::: "memory");
+  __asm__ volatile ("" ::: "memory");
 #else
   secure_memset(buf, 0, sz);
 #endif