egl: Link drivers back to libEGL.

Drivers need symbols from libEGL.  Without back-linking, the build fails
on Cygwin.

src/egl/drivers/Makefile.template

@@ -26,7 +26,7 @@ $(EGL_DRIVER): $(EGL_OBJECTS) Makefile $(TOP)/src/egl/drivers/Makefile.template
 	@$(MKLIB) -o $(EGL_DRIVER) -noprefix \
 		-linker '$(CC)' -ldflags '$(LDFLAGS)' \
 		-L$(TOP)/$(LIB_DIR) $(MKLIB_OPTIONS) \
-		$(EGL_OBJECTS) $(EGL_LIBS)
+		$(EGL_OBJECTS) $(EGL_LIBS) -l$(EGL_LIB)
 
 .c.o:
 	$(CC) -c $(EGL_INCLUDES) $(CFLAGS) $(EGL_CFLAGS) $< -o $@

src/gallium/targets/Makefile.egl

@@ -56,7 +56,7 @@ $(MKLIB) -o $@ -noprefix -linker '$(CC)' -ldflags '$(LDFLAGS)' \
 	$(MKLIB_OPTIONS) $(EGL_DRIVER_OBJECTS) \
 	-Wl,--start-group $($(1)_ST) $(EGL_DRIVER_PIPES) \
 	$(GALLIUM_AUXILIARIES) -Wl,--end-group \
-	$($(1)_LIBS) $(EGL_DRIVER_LIBS)
+	$($(1)_LIBS) $(EGL_DRIVER_LIBS) -L$(TOP)/$(LIB_DIR) -l$(EGL_LIB)
 endef
 
 egl_x11_$(EGL_DRIVER_NAME).so: $(EGL_DRIVER_OBJECTS) $(x11_ST) $(EGL_DRIVER_PIPES) $(GALLIUM_AUXILIARIES) Makefile