Add a script to check whether the compiler supports a certain flag

[jdemeyer]

We should add a script testcflag.sh in the spirit of testcc.sh which simply tests whether the C compiler supports a certain command-line flag.

Apply attachment: 12367_testcflags.patch to the SAGE_ROOT repository.

Component: build

Author: Jeroen Demeyer

Reviewer: R. Andrew Ohana

Merged: sage-5.0.beta4

Issue created by migration from https://trac.sagemath.org/ticket/12367

[jdemeyer]

Attachment: 12367_testcflags.patch.gz

[jdemeyer]

Description changed:

--- 
+++ 
@@ -1 +1,3 @@
 We should add a script `testcflag.sh` in the spirit of `testcc.sh` which simply tests whether the C compiler supports a certain command-line flag.
+
+Apply [attachment: 12367_testcflags.patch](https://github.com/sagemath/sage-prod/files/10654631/12367_testcflags.patch.gz) to the `SAGE_ROOT` repository.

[ohanar]

comment:2

works as expected and looks good to me

[ohanar]

Reviewer: R. Andrew Ohana

[jdemeyer]

Merged: sage-5.0.beta4