build: clean up some unnecessary cached variables
build: clean up some unnecessary cached variables

The CMAKE_<LANG>_ARCHIVE_FINISH rule doesn't need to be cleared for Darwin
static libraries.  Avoid resetting the variables in the SIP case.  If
CMAKE_RANLIB is cached, then CMake's Ninja generator will invoke ranlib during
installation, not due to the CMAKE_<LANG>_ARCHIVE_FINISH rule.

git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@342511 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt