fixup! Add support for f128 integer exponentiation

Author: tgross35

testcrate/src/lib.rs

@@ -342,8 +342,9 @@ macro_rules! apfloat_fallback {
 // `__multf3` is now available in nightly, but `__divtf3` is not yet. Provide a fallback until
 // that happens.
 #[no_mangle]
+#[linkage = "weak"]
 #[cfg(target_env = "msvc")]
-#[cfg(not(feature = "no-f16-f128"))]
+#[cfg(all(feature = "mangled-names", not(feature = "no-f16-f128")))]
 pub extern "C" fn __divtf3(a: f128, b: f128) -> f128 {
     compiler_builtins::float::div::__divtf3(a, b)
 }