libforms: Replace hardcoded dep on mesa with virtual/libgl

This ensures that it can be built on machines with non-mesa graphics
drivers

Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-oe/recipes-graphics/libforms/libforms_1.2.5pre1.bb

@@ -20,7 +20,7 @@ REQUIRED_DISTRO_FEATURES = "opengl x11"
 
 S = "${WORKDIR}/xforms-${PV}"
 
-DEPENDS = "libxpm jpeg libx11 mesa"
+DEPENDS = "libxpm jpeg libx11 virtual/libgl"
 RDEPENDS:${PN} = "bash"
 
 EXTRA_OECONF = "--with-extra-inc=${S}/lib"