Fix glibc assert: __assert -> __assert_fail

[Connor-GH]

ldc2 returns SIGSEGV instead of SIGABRT for any value of assert in betterC (or -checkaction=C or defaultlib="" ...) due to some improper usage of __assert. As per the C compilers, (gcc, clang, etc.), __assert_fail should be used for C asserts.

See my related PR for DMD:

https://github.com/dlang/dmd/pull/16515

[Connor-GH]

https://issues.dlang.org/show_bug.cgi?id=24558

[kinke]

Is there an upstream test for this?

[thewilsonator]

No there is not