[GWP_ASAN] Avoid using VERSION_GREATER_EQUAL in cmake files

This is a fixup for r369823 which introduced the use of
VERSION_GREATER_EQUAL in the cmake config for gwp_asan.

Minimum supported version of cmake in LLVM is 3.4.3 and
VERSION_GREATER_EQUAL was not introduced until later
versions of cmake.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@369891 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed