Both 'head -n 1' and 'sed 1q' exit after printing the first line, which closes
the pipe and kills the compiler's process leaving it no chance to clean any
temporary files it might have created (e.g. Intel compiler creates 'a.out' when
it is called with additional flags like -I, -L, etc., which is the case when
$CC/$FC is an MPI wrapper.

And make sure that the result is the same as for Fortran (FC).

The conditional indicates that FC is available and all required compiler flags
are known.

Instead of tinkering its analogue.

Thomas Jahns authored 5 years ago and Sergey Kosukhin committed 3 years ago

* Given how many lines documenting the confusing pattern and how many
  compiler warnings are eliminated by this change...

The Debian version of Libtool fails to build.