Bug #233077 - Add QA check which verifies that LDFLAGS are respected. For now

Bug #233077 - Add QA check which verifies that LDFLAGS are respected. For now
this only works when LDFLAGS contains --hash-style=gnu since in this case the
the elf files should not contain .hash sections and we can use scanelf to
check whether or not the those sections exist. This adds a QA_DT_HASH variable
that is analogous to existing QA control variables documented in the ebuild.5
man page. There is also a complementary QA_STRICT_DT_HASH variable that can
be set in make.conf in order to ignore QA_DT_HASH settings in ebuilds. Thanks
to Arfrever Frehtes Taifersar Arahesis for this patch which I've tweaked in
just a few minor ways.

svn path=/main/trunk/; revision=11205