216db5e051
When building compiler-rt with MSVC, CMAKE_INSTALL_LIBDIR and
CMAKE_INSTALL_BINDIR are empty.
This causes error in Findzstd.cmake like the following:
CMake Error at C:/llvm/cmake/modules/Findzstd.cmake:39 (string):
string sub-command REGEX, mode REPLACE: regex "$" matched an empty
string.
Do not do the REGEX when CMAKE_INSTALL_LIBDIR and CMAKE_INSTALL_BINDIR
are empty.
Similar issues were reported by others at
e7fc7540da
See docs/CMake.html for instructions on how to build LLVM with CMake.