configure: check for dladdr via AC_CHECK_FUNC/AC_CHECK_LIB
Use both macros as in some cases using AC_CHECK_FUNCS alone may fail.
Thus HAVE_DLADDR will not be defined, and as a result most of the code
in megadriver_stub.c will not be compiled. Breaking the backwards
compatibility between older libGL/xserver(s) and DRI megadrivers.
Cc: Jon TURNEY <jon.turney@dronecode.org.uk>
Cc: "10.2" <mesa-stable@lists.freedesktop.org>
[Emil Velikov] Commit message.
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>