Add find-debuginfo.sh -m minisymtab support.

Add find-debuginfo.sh -m minisymtab support.

Support for minisymtab (a minimal function symbol table in a compressed
section in the main binary) has been in gdb and elfutils based tools
since some years. Fedora has had this as rpm-4.10.0-minidebuginfo.patch
since 2012.

The patch adjusts macros to pass -m to find-debuginfo.sh when
_include_minidebuginfo has been set. find-debuginfo.sh now takes -m
as argument to generate the .gnu_debugdata ELF section to be added
to the main executable.

To support the testcases a new macros.debug is added that is used to
generate debuginfo packages in the rpmbuild.at testsuite.

The original support was added to Fedora rpm by Alexander Larsson.
Lubos Kardos fixed a bug in it when strip -g was used. I added some
configuration macros and two testcases to check the basic support works
and for the strip -g bug.

Signed-off-by: Mark Wielaard <mjw@redhat.com>