[cmake] Always respect existing CMAKE_REQUIRED_FLAGS when adding additional ones.
Summary:
Always respect existing CMAKE_REQUIRED_FLAGS when adding
additional ones. This is important when cross compiling where
--sysroot and -target were already added.
In particular, this is needed when cross compiling from Darwin to
Linux, since --sysroot is required to find headers and libraries.
Cmake has a similar bug in check_include_file[_cxx] where
CMAKE_REQUIRED_LIBRARIES isn't passed, which causes
try_compile to fail.
(please see https://gitlab.kitware.com/cmake/cmake/merge_requests/1620)
Reviewers: compnerd, silvas, beanz, brad.king
Reviewed By: compnerd
Subscribers: mgorny, llvm-commits
Differential Revision: https://reviews.llvm.org/D41568
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@321434 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed