graphviz: fix webp plugin loading

packages/graphviz/build.sh

@@ -2,6 +2,7 @@ TERMUX_PKG_HOMEPAGE=https://www.graphviz.org/
 TERMUX_PKG_DESCRIPTION="Rich set of graph drawing tools"
 TERMUX_PKG_LICENSE="EPL-2.0"
 TERMUX_PKG_VERSION=2.44.1
+TERMUX_PKG_REVISION=1
 TERMUX_PKG_SRCURL=https://www2.graphviz.org/Packages/stable/portable_source/graphviz-$TERMUX_PKG_VERSION.tar.gz
 TERMUX_PKG_SHA256=8e1b34763254935243ccdb83c6ce108f531876d7a5dfd443f255e6418b8ea313
 TERMUX_PKG_DEPENDS="libandroid-glob, libc++, libcairo, pango, libexpat, libltdl, librsvg, libgd, zlib"

packages/graphviz/plugin-webp-Makefile.am.patch

@@ -0,0 +1,12 @@
+diff -uNr graphviz-2.44.1/plugin/webp/Makefile.am graphviz-2.44.1.mod/plugin/webp/Makefile.am
+--- graphviz-2.44.1/plugin/webp/Makefile.am	2020-06-29 11:47:18.000000000 +0300
++++ graphviz-2.44.1.mod/plugin/webp/Makefile.am	2020-08-09 22:58:32.615146633 +0300
+@@ -26,7 +26,7 @@
+ 
+ libgvplugin_webp_la_LDFLAGS = -version-info @GVPLUGIN_VERSION_INFO@
+ libgvplugin_webp_la_SOURCES = $(libgvplugin_webp_C_la_SOURCES)
+-libgvplugin_webp_la_LIBADD = @WEBP_LIBS@ @PANGOCAIRO_LIBS@
++libgvplugin_webp_la_LIBADD = $(top_builddir)/lib/gvc/libgvc.la @WEBP_LIBS@ @PANGOCAIRO_LIBS@
+ 
+ if WITH_WIN32
+ libgvplugin_webp_la_LDFLAGS += -no-undefined