Ticket 31687: fix for tor_isinf() as well

tor_isinf() was new in 0.4.0, and also needs to look at the
same rules as clamp_double_to_i64()

src/lib/math/fp.c

@@ -127,16 +127,12 @@ int
 tor_isinf(double x)
 {
   /* Same as above, work around the "double promotion" warnings */
-#if defined(MINGW_ANY) && GCC_VERSION >= 409
-#define PROBLEMATIC_FLOAT_CONVERSION_WARNING
+#ifdef PROBLEMATIC_FLOAT_CONVERSION_WARNING
 DISABLE_GCC_WARNING(float-conversion)
-#endif /* defined(MINGW_ANY) && GCC_VERSION >= 409 */
-#if defined(__clang__)
-#if __has_warning("-Wdouble-promotion")
-#define PROBLEMATIC_DOUBLE_PROMOTION_WARNING
+#endif
+#ifdef PROBLEMATIC_DOUBLE_PROMOTION_WARNING
 DISABLE_GCC_WARNING(double-promotion)
 #endif
-#endif /* defined(__clang__) */
   return isinf(x);
 #ifdef PROBLEMATIC_DOUBLE_PROMOTION_WARNING
 ENABLE_GCC_WARNING(double-promotion)
@@ -145,4 +141,3 @@ ENABLE_GCC_WARNING(double-promotion)
 ENABLE_GCC_WARNING(float-conversion)
 #endif
 }
-