message: fast_math.hpp: Use __asm__ rather than asm; fixes including with -std=c99
diff: int res; \
  float temp; \
  (void)temp; \
  - asm(_asm_string : [res] "=r" (res), [temp] "=w" (temp) : [value] "w" (_value)); \
  + __asm__(_asm_string : [res] "=r" (res), [temp] "=w" (temp) : [value] "w" (_value)); \
  return res
  // 2. version for double
  #ifdef __clang__
  