at least the AMD (aocc) flavor of flang wants to link to a (real or dummy) libomp by default

fixes #2336 (non-recognition of gcc 10) with patch provided by JeffreyALaw.

Both forms are seen on NetBSD (#2288)

Auto-add "-fno-second-underscore" option to make LAPACKE compile (as it calls LAPACK functions that may have gotten a second underscore added otherwise). Also support -R for rpath when parsing compiler directives in f_check

Found via `codespell -q 3 -w -L ith,als,dum,nd,amin,nto,wis,ba -S ./relapack,./kernel,./lapack-netlib`

1. the already deprecated -openmp option was removed in 2018, switch to -fopenmp
2. add leading blank in search for "zho_ge__" symbol to work around misleading tags in the 2018 assembly
Expected to fix #1548

- retry fortran compiler test with aix-specific option if generic -m32/-m64 fails
- pass any custom ARFLAGS to lapack
- no addition of -m32/-m64 to the CFLAGS and FFLAGS on AIX

Without proper recognition of gfortran versions such as
> GNU Fortran (GCC) 4.9.x 20150123 (prerelease)
OpenBLAS assumes the presence of the G77 compiler. Consequently,
`-lgfortran` is missing from the pkg-config file.

The aforementioned compiler is the gfortran compiler in the Android repo
in a commit tagged as `ndk-r14`, cf. Paul Mustière's gfortran build
instructions for Android at https://github.com/buffer51/android-gfortran

Signed-off-by: Paul Osmialowski <pawel.osmialowski@arm.com>

Fixes build with TDM-GCC

Signed-off-by: Shivraj Patil <shivraj.patil@imgtec.com>

Signed-off-by: Shivraj Patil <shivraj.patil@imgtec.com>

Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>

Signed-off-by: Shivraj Patil <shivraj.patil@imgtec.com>

the illumos linker can't understand the "-Y/lib"... form that f_check
generates, and -Wl cannot pass options that include commas

2) If OpenBLAS cannot find Fortran compiler, it will only build BLAS
(without LAPACK).

On FreeBSD, passing extra options to `which` causes it to report a non-zero status:

```
$ which gfortran48 -m64
/usr/local/bin/gfortran48
$ echo $?
1
```

```
$ which gfortran48
/usr/local/bin/gfortran48
$ echo $?
0
```

Signed-off-by: Timothy Gu <timothygu99@gmail.com>

- Test with '-x' operator to ensure file is executable.
- 'break' is not a valid Perl keyword.