This removes the hard-coded (and incorrect) paths to the libc++ and libc++abi
static libraries in favor of just using the already provided library path and the library
names with the '-l' option.
#rb none
#preflight skip
[CL 19545833 by matt johnson in ue5-main branch]
This represents UE4/Main @18073326, Release-5.0 @18081140 and Dev-PerfTest @18045971
[CL 18081471 by aurel cordonnier in ue5-release-engine-test branch]