COMP: Suppress some Wformat-nonliteral warnings

[seanm]

Introduced GCC_PRAGMA_PUSH macro and friends, similiar to existing CLANG_PRAGMA_PUSH and friends, but that applies to both GCC and Clang, which share many warning flags.

Added macros to suppess -Wformat-nonliteral warnings. Used them in a few places where the warnings are impossible to fix with ITK's current API.

Made -Wfloat-equal apply to GCC now, in addition to Clang.

Also added these macros as StatementMacros in the .clang-format file, so that clang-format formats them more nicely. Redid some formatting.

PR Checklist

• [ ] No API changes were made (or the changes have been approved)
• [ ] No major design changes were made (or the changes have been approved)
• [ ] Added test (or behavior not changed)
• [ ] Updated API documentation (or API not changed)
• [ ] Added license to new files (if any)
• [ ] Added Python wrapping to new files (if any) as described in ITK Software Guide Section 9.5
• [ ] Added ITK examples for all new major features (if any)

Refer to the ITK Software Guide for further development details if necessary.

[seanm]

This should fix some of these warnings:

https://open.cdash.org/viewBuildError.php?type=1&buildid=9572940

[hjmjohnson]

@seanm Ran clang-formatter:

./Utilities/Maintenance/clang-format.bash --clang-format /Users/johnsonhj/Dashboard/src/ITK/cmake-build-release/clang-format-Darwin --tracked

[seanm]

Thanks for the touch-ups!

[SimonRit]

This PR has removed CLANG_SUPPRESS_Wfloat_equal which was used in my code: https://my.cdash.org/viewBuildError.php?buildid=2552633 There is a quick fix of course but other users might still use CLANG_SUPPRESS_Wfloat_equal. Was this intentional? I wonder why it's not been kept since CLANG_PRAGMA_PUSH and CLANG_PRAGMA_POP have been kept.

[seanm]

Hmm, although it's in a public header, I didn't imaging anyone using it.

I'll make a new MR to bring it back. Probably not until later today though, as I'm just recovering from a stomach bug.

[seanm]

@SimonRit https://github.com/InsightSoftwareConsortium/ITK/pull/4644