paraview: fix for x86_64-musl.

The build system doesn't pick up the execinfo dependency properly, so
fixing the linking portion requires manual intervention.

srcpkgs/paraview/template

@@ -17,6 +17,7 @@ configure_args="-DCMAKE_PREFIX_PATH=${XBPS_CROSS_BASE}/usr
  -DVTKm_USE_DOUBLE_PRECISION=ON"
 #make_build_args="VERBOSE=1"
 hostmakedepends="pkg-config which"
+# TODO: find some way of making this work with system vtk
 makedepends="MesaLib-devel libfreeglut-devel glu-devel libXt-devel
  openmpi-devel qt5-devel qt5-x11extras-devel qt5-tools-devel qt5-plugin-mysql
  qt5-plugin-odbc qt5-plugin-pgsql qt5-plugin-sqlite qt5-plugin-tds
@@ -41,15 +42,23 @@ export QT_SELECT="5"
 
 if [ "$XBPS_TARGET_LIBC" = musl ]; then
 	makedepends+=" libexecinfo-devel"
+	LDFLAGS="-lexecinfo"
 fi
 if [ "$XBPS_TARGET_NO_ATOMIC8" ]; then
 	makedepends+=" libatomic-devel"
 fi
 
+case "$XBPS_MACHINE" in
+	# TODO: is this necessary for other kinds of 32bit builders?
+	i686*) # XXX: this might be necessary if the i686 builder dies due to OOM
+	: disable_parallel_build="https://build.voidlinux.org/builders/i686_builder/builds/27013/steps/shell_3/logs/stdio"
+	;;
+esac
+
 case "$XBPS_TARGET_MACHINE" in
-	x86_64) ;;
-	*) # broken for all other targets
-	broken="https://build.voidlinux.org/builders/i686_builder/builds/27013/steps/shell_3/logs/stdio"
+	x68_64*|i686*) ;;
+	*)
+	broken="uncertain why; currently being tested"
 	;;
 esac
 
@@ -60,6 +69,25 @@ post_extract() {
 	fi
 }
 
+_add_execinfo() {
+	# contents of link.txt files need to be in a single line
+	local content="$(cat $1) -lexecinfo "
+	echo "$content" > $1
+}
+
+pre_build() {
+	if [ "$XBPS_TARGET_LIBC" = musl ]; then
+		# TODO: -lexecinfo in LDFLAGS adds it to the start of the file, so linking still fails.
+		# there's probably some configure_arg that actually makes it work cleanly, I hope.
+		# this list of files hasn't been extensively tested. It's possible not all of them are required.
+		_add_execinfo build/VTK/Rendering/LICOpenGL2/CMakeFiles/RenderingLICOpenGL2.dir/link.txt
+		_add_execinfo build/VTK/Rendering/OpenGL2/CMakeFiles/vtkProbeOpenGLVersion.dir/link.txt
+		_add_execinfo build/VTK/ThirdParty/loguru/vtkloguru/CMakeFiles/loguru.dir/link.txt
+		_add_execinfo build/VTK/Common/Core/CMakeFiles/CommonCore.dir/link.txt
+		_add_execinfo build/VTKExtensions/Core/CMakeFiles/VTKExtensionsCore.dir/link.txt
+	fi
+}
+
 post_install() {
 	vlicense Copyright.txt
 }