Fix CMake Compiler Flag Summary: ID Regex Matching

[nmnobre]

Fixes #2978.

Summary

To understand what I'm trying to fix here, first note:

amrex/Tools/CMake/AMReXFlagsTargets.cmake

Lines 71 to 95 in b3f6738

	target_compile_options( Flags_CXX
	INTERFACE
	$<${_cxx_gnu_dbg}:-O0 -ggdb -Wall -Wno-sign-compare -Wno-unused-but-set-variable -Werror=return-type>
	# $<$<VERSION_GREATER:$<CXX_COMPILER_VERSION>,5.0>:-Wnull-dereference>
	$<${_cxx_gnu_rwdbg}:-Werror=return-type>
	$<${_cxx_gnu_rel}:-Werror=return-type>
	$<${_cxx_intel_dbg}:-O0 -traceback -Wcheck>
	$<${_cxx_intel_rwdbg}:-ip -qopt-report=5 -qopt-report-phase=vec>
	$<${_cxx_intel_rel}:-ip -qopt-report=5 -qopt-report-phase=vec>
	$<${_cxx_pgi_dbg}:-O0 -Mbounds>
	$<${_cxx_pgi_rwdbg}:-gopt -fast>
	$<${_cxx_pgi_rel}:-gopt -fast>
	$<${_cxx_cray_dbg}:-O0>
	$<${_cxx_cray_rwdbg}:>
	$<${_cxx_cray_rel}:>
	$<${_cxx_clang_dbg}:-O0 -Wall -Wextra -Wno-sign-compare -Wno-unused-parameter -Wno-unused-variable>
	$<${_cxx_clang_rwdbg}:>
	$<${_cxx_clang_rel}:>
	$<${_cxx_appleclang_dbg}:-O0 -Wall -Wextra -Wno-sign-compare -Wno-unused-parameter -Wno-unused-variable>
	$<${_cxx_appleclang_rwdbg}:>
	$<${_cxx_appleclang_rel}:>
	$<${_cxx_intelllvm_dbg}:-O0 -Wall -Wextra -Wno-sign-compare -Wno-unused-parameter -Wno-unused-variable>
	$<${_cxx_intelllvm_rwdbg}:-gline-tables-only -fdebug-info-for-profiling> # recommended by Intel VTune
	$<${_cxx_intelllvm_rel}:>
	)

Then, with Intel's classic compilers, configure AMReX with -DCMAKE_BUILD_TYPE=Debug and note the C++ flags listed under "AMReX configuration summary", before and after the changes suggested here. The gist is Intel as a compiler id was matching IntelLLVM (and Clang was also matching AppleClang though the flags in that case are the same, so it's harder to tell).
EDIT: this actually only affects what's printed in the summary, the flags that are actually used are already correct!

The proposed changes:

• fix a bug or incorrect behavior in AMReX
• add new capabilities to AMReX
• changes answers in the test suite to more than roundoff level
• are likely to significantly affect the results of downstream AMReX users
• include documentation in the code and/or rst files, if appropriate

[ax3l]

Can you help me understand what the change in regex does for each part?

• Does [:,] now match a literal : or ,?
• Does [>,] now match a literal > or ,?

[nmnobre]

• Does [:,] now match a literal : or ,?
• Does [>,] now match a literal > or ,?

Yes to both, the idea is that we will now exactly (without prefixes or suffixes) match ${_comp} because it must be surrounded by commas (if it's in the middle of the list) or immediately follow the colon at the beginning of the list or immediately precede the chevron at the end of the list.

[WeiqunZhang]

It would also match $<CXX_COMPILER_ID,someid>, right?

[nmnobre]

Right, but that's illegal CMake syntax and will cause CMake to complain with "Expression did not evaluate to a known generator expression" or "Expression syntax not recognized."

[ax3l]

LGTM, more robust 👍