Merge rust-lang/libm#93

93: fdimf r=japaric a=jackmott

closes rust-lang/libm#47 

Co-authored-by: Jack Mott <jack.mott@gmail.com>

library/compiler-builtins/libm/test-generator/src/main.rs

@@ -662,7 +662,6 @@ f32_f32! {
     // coshf,
     // exp2f,
     expf,
-    // fdimf,
     log10f,
     log1pf,
     log2f,
@@ -679,6 +678,7 @@ f32_f32! {
 // With signature `fn(f32, f32) -> f32`
 f32f32_f32! {
     // atan2f,
+    fdimf,
     hypotf,
     fmodf,
     powf,
@@ -724,7 +724,7 @@ f64_f64! {
 // With signature `fn(f64, f64) -> f64`
 f64f64_f64! {
     // atan2,
-    // fdim,
+    fdim,
     // fmod,
     hypot,
     // pow,