The futex-based implementation of libxshmfence requires atomic operations

that hppa, m88k and sh don't provide.  Since DRI3 requires libxshmfence,
this means we can't enable DRI3 on these platforms.

ok matthieu@

lib/Makefile

@@ -1,4 +1,4 @@
-# $OpenBSD: Makefile,v 1.36 2018/06/26 06:51:17 kettenis Exp $
+# $OpenBSD: Makefile,v 1.37 2018/06/28 20:11:32 kettenis Exp $
 
 .include <bsd.xconf.mk>
 
@@ -44,7 +44,11 @@ SUBDIR= freetype fontconfig libxtrans libXau libXdmcp ${XCB_LIBS}\
 	libXi libXinerama libxkbfile libxkbui  \
 	libXrandr libXRes libXScrnSaver \
 	libXtst libXv libXvMC libXxf86dga libXxf86vm \
-	libpciaccess libxshmfence pixman
+	libpciaccess pixman
+
+.if ${XENOCARA_BUILD_DRI3:L} == "yes"
+SUBDIR+= libxshmfence
+.endif
 
 .if ${XENOCARA_BUILD_GL:L} == "yes"
 SUBDIR+= libdrm

lib/mesa/Makefile.bsd-wrapper

@@ -1,6 +1,7 @@
-# $OpenBSD: Makefile.bsd-wrapper,v 1.18 2018/06/26 06:51:17 kettenis Exp $
+# $OpenBSD: Makefile.bsd-wrapper,v 1.19 2018/06/28 20:11:32 kettenis Exp $
 
 .include <bsd.own.mk>
+.include <bsd.xconf.mk>
 
 SHARED_LIBS=	EGL 1.1 gbm 0.2 glapi 0.2 GL 17.1 GLESv1_CM 1.0 GLESv2 1.2 \
 		OSMesa 11.0
@@ -30,12 +31,15 @@ CONFIGURE_ARGS=		--with-dri-drivers=${DRI_DRIVERS} \
 			--enable-osmesa \
 			--enable-gbm \
 			--enable-texture-float \
-			--enable-dri3 \
 			--with-egl-platforms="x11,drm" \
 			--prefix=${X11BASE} \
 			--with-dri-driverdir=${X11BASE}/lib/modules/dri \
 			--with-dri-searchpath=${X11BASE}/lib/modules/dri
 
+.if ${XENOCARA_BUILD_DRI3:L} == "yes"
+CONFIGURE_ARGS+=	--enable-dri3
+.endif
+
 # The i965 driver uses the cmpxchg8b instruction
 .if ${MACHINE} == i386
 CONFIGURE_ARGS+=	USER_CFLAGS="-march=i586" USER_CXXFLAGS="-march=i586"

share/mk/bsd.xconf.mk

@@ -1,4 +1,4 @@
-# $OpenBSD: bsd.xconf.mk,v 1.34 2016/04/01 03:15:15 jsg Exp $
+# $OpenBSD: bsd.xconf.mk,v 1.35 2018/06/28 20:11:32 kettenis Exp $
 
 # Build GL libs and apps?
 .if ${MACHINE_ARCH} == "m88k"
@@ -8,3 +8,11 @@ XENOCARA_BUILD_DRI?=no
 XENOCARA_BUILD_GL?=yes
 XENOCARA_BUILD_DRI?=yes
 .endif
+
+# Build DRI3 support?
+.if ${XENOCARA_BUILD_DRI:L} == "no" || ${MACHINE_ARCH} == "hppa" || \
+    ${MACHINE_ARCH} == "sh"
+XENOCARA_BUILD_DRI3?=no
+.else
+XENOCARA_BUILD_DRI3?=yes
+.endif