By using commmon/gcc-base-unix.conf and common/g++-unix.conf most of
the contents of the qmake.conf for OpenBSD can go. The QMAKE_LFLAGS_UNDEF
are reset because the linker can't handle environ in libraries, which is
only added to libc in OpenBSD 6 (http://www.openbsd.org/faq/current.html)
even when explicitly adding -lc to QMAKE_LIBS.

See
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20151102/309783.html


for similar questions on using -Wl,-z,defs instead.

Change-Id: I6c725fb3bc7ae63270912b07f230a480c9157dfd
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>