graphics/libosmesa: Remove expat from LIB_DEPENDS

It's not needed for this mesa component.

Differential Revision:	https://reviews.freebsd.org/D44828
PR:			278324
Reported by:		autodep
Reviewed by:		bapt
Sponsored by:		Beckhoff Automation GmbH & Co. KG

graphics/libosmesa/Makefile

@@ -1,5 +1,6 @@
 PORTNAME=	libosmesa
 PORTVERSION=	${MESAVERSION}
+PORTREVISION=	1
 CATEGORIES=	graphics
 
 COMMENT=	Off-Screen Mesa implementation of the OpenGL API

graphics/mesa-dri/Makefile.common

@@ -35,14 +35,14 @@ LICENSE_FILE=	${WRKSRC}/docs/license.rst
 COMPONENT=	${PORTNAME:tl:C/^lib//:C/mesa-//}
 
 BUILD_DEPENDS+=	${PYTHON_PKGNAMEPREFIX}mako>0:textproc/py-mako@${PY_FLAVOR}
-LIB_DEPENDS+=	libexpat.so:textproc/expat2
 .if ${COMPONENT} != clover
 .if ${PORT_OPTIONS:MPLATFORM_X11}
 USES+=	xorg
 .endif
 .endif
 .if ${COMPONENT} != osmesa
-LIB_DEPENDS+=	libdrm.so:graphics/libdrm
+LIB_DEPENDS+=	libdrm.so:graphics/libdrm \
+		libexpat.so:textproc/expat2
 .endif
 
 USES+=		compiler:c++11-lib bison meson pathfix pkgconfig \