gallium: work around libtool relink issue for libdrm

gallium: work around libtool relink issue for libdrm

This is similar to commit 90633079. libtool links first to system directories
instead of custom locations of libdrm on relinking. Since a more recent libdrm
version than the one provided by the system is often needed when compiling
mesa, make sure this works by putting libdrm in front.

See also: https://bugs.freedesktop.org/show_bug.cgi?id=100259

Signed-off-by: Roman Gilg <subdiff@gmail.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>