m4/ax_detect_clang.m4: preserve clang specific CPPFLAGS across clang-cpp check
commita1e1ae65230700ea07c6d7037031b5e009838183
authorSven Verdoolaege <sven.verdoolaege@gmail.com>
Fri, 31 Mar 2023 20:38:21 +0000 (31 22:38 +0200)
committerSven Verdoolaege <sven.verdoolaege@gmail.com>
Sat, 1 Apr 2023 15:32:08 +0000 (1 17:32 +0200)
treed216f611a4410386b9fd8b64c9bd5a988e31cc38
parentaaf601ce3067f877e2ab3fe235c9bbdf680d8899
m4/ax_detect_clang.m4: preserve clang specific CPPFLAGS across clang-cpp check

This will be needed in the next commit, to compile (and link)
a test program.
For simplicity, save and restore all modified flags together.

Signed-off-by: Sven Verdoolaege <sven.verdoolaege@gmail.com>
m4/ax_detect_clang.m4