v4.0.x: Make sure MPIR_Breakpoint() is compiled without CFLAGS.

[awlauria]

In optimized builds, CFLAGS contains various optimizations such as -O3,
and is propogated by automake to all files. To work-around this,
isolate MPIR_Breakpoint() and other MPIR_* symbols into its own library
built with debugger specific CFLAGS.

To prevent CFLAGS from being polluted elsewhere in the make tree, build
this in its own tiny stand-alone makefile.

Fixes #7757

Signed-off-by: Austen Lauria [email protected]

NOTE: This is not a cherry-pick from master because ORTE no longer exists on master.

[jjhursey]

bot:ibm:retest

[gpaulsen]

I did a line-by-line review of this with Austen, and this looks fine.
It's a shame we have to go to such lengths to specify a different CFLAGS for a file, but creating a more generic system would be more work, and this is the only file that really NEEDs it.
Austen will post his build log showing that this indeed dropped the Opt level to -O0 for this particular file.
Austen will also PR this to v4.1.x, as no orte in master.

[jjhursey]

Thanks for fighting through the build system to do this.
It is unfortunate that we have to manipulate the build system in this way, but there are worse sins I suppose :)

[awlauria]

I agree that we should fix this more generally. But for the 4.x release series it's good. Going forward I might keep plugging away at removing the global CFLAGS in my free time and post that PR if the community wants it.

[awlauria]

Here's a piece of the make V=1 output showing only this file is compiled without O3:

out.txt

[gpaulsen]

@jsquyres Please review.