Add ax_check_gl_m4.patch from Fedora for adding LDFLAGS, fixes RELRO

Currently namcap gives the following output for the current repo pkg:

chromium-bsu W: ELF file ('usr/bin/chromium-bsu') lacks FULL RELRO, check LDFLAGS.
chromium-bsu E: custom:artistic is not a valid SPDX license identifier. See https://spdx.org/licenses/ for valid identifiers, or prefix the identifier with 'LicenseRef-', if it is custom.
chromium-bsu W: Unused shared library '/usr/lib/libOpenGL.so.0' by file ('usr/bin/chromium-bsu')
chromium-bsu W: Unused shared library '/usr/lib/libfreetype.so.6' by file ('usr/bin/chromium-bsu')
chromium-bsu E: Dependency hicolor-icon-theme detected and not included (needed for hicolor theme hierarchy)
chromium-bsu W: Dependency libglvnd detected and implicitly satisfied (libraries ['usr/lib/libOpenGL.so.0', 'usr/lib/libGL.so.1'] needed in files ['usr/bin/chromium-bsu'])
chromium-bsu W: Dependency glibc detected and implicitly satisfied (libraries ['usr/lib/libm.so.6', 'usr/lib/libc.so.6'] needed in files ['usr/bin/chromium-bsu'])
chromium-bsu W: Dependency freetype2 detected and implicitly satisfied (libraries ['usr/lib/libfreetype.so.6'] needed in files ['usr/bin/chromium-bsu'])
chromium-bsu W: Dependency sdl2-compat detected and implicitly satisfied (libraries ['usr/lib/libSDL2-2.0.so.0'] needed in files ['usr/bin/chromium-bsu'])
chromium-bsu W: Dependency gcc-libs detected and implicitly satisfied (libraries ['usr/lib/libgcc_s.so.1', 'usr/lib/libstdc++.so.6'] needed in files ['usr/bin/chromium-bsu'])

The most important is the RELRO warning, the accompanying patch includes LDFLAGS from Arch, the description says the patch is from Debian but AFAIK only Fedora seems to use it at present, Debian only uses another patch. This and the other changes causes namcap to give no output, which is good.