[gdb] Clean whitespace in *.ac and *.m4 files

[gdb] Clean whitespace in *.ac and *.m4 files

This is the result of:
...
$ git rm -f $(find gdb* -name "*.ac")
$ git rm -f $(find gdb* -name "*.m4")
$ git commit -a -m tmp
$ git revert HEAD
$ git rebase --whitespace=fix HEAD^
$ git reset --soft HEAD^
$ git commit --amend
...
and running autoreconf -f in directories gdb, gdb/testsuite, gdbsupport and
gdbserver.

Tested on x86_64-linux.

Approved-By: Simon Marchi <simon.marchi@efficios.com>