Using GL for the PKG_CHECK_MODULES identifier multiple times means only
the first call will actually be used. Later calls will be skipped due to
GL_CFLAGS and GL_LIBS already being set. This changes DRI to using a
different identifier and DMX to just reusing GL_CFLAGS.
Signed-off-by: Dan Nicholson <dbn.lists@gmail.com>
Get rid of almost all uses of these definitions. They're still defined for
delinquent out-of-tree drivers, and also for the Mesa build. As well as
for miinitext.c. But largely gone.
Don't try to build dmx/input/usb-*.c if <linux/input.h> isn't found
Replace -rdynamic with $(LD_EXPORT_SYMBOLS_FLAG) for compatibility with
compilers other than gcc
