floating point intrinsics may clobber errno in unrelated code #12695
Description
These intrinsics assume errno is not set, but it may be set. In theory, one of these intrinsics could be reordered between a call to a C function setting errno and a check of the errno value in Rust. Rust could ignore this problem, as it will rarely (if ever) occur. However, safety mandates that we either supply our own math library known to not set errno on math errors (glibc is a black sheep in this regard) or stop using these unless something like -fno-math-errno is passed (as clang handles it on Linux).