gst1-plugins-bad: fix openh264 handling

Commit 301e8ffbb25 (gst1-plugins-bad: update configure options) added a sub
option for openh264, but didn't propagate the toolchain dependencies or add
any configure options.

Fix this and while we're at it also add a help text for the option.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/gstreamer1/gst1-plugins-bad/Config.in

@@ -595,7 +595,18 @@ comment "opencv plugin needs OpenCV-2.4"
 
 config BR2_PACKAGE_GST1_PLUGINS_BAD_PLUGIN_OPENH264
 	bool "openh264"
+	depends on BR2_PACKAGE_LIBOPENH264_ARCH_SUPPORTS
+	depends on BR2_INSTALL_LIBSTDCPP # libopenh264
+	depends on !BR2_STATIC_LIBS # libopenh264
+	depends on BR2_TOOLCHAIN_HAS_THREADS # libopenh264
 	select BR2_PACKAGE_LIBOPENH264
+	help
+	  OpenH264 based encoding/decoding plugin
+
+comment "openh264 plugin needs a toolchain w/ C++, dynamic library, threads"
+	depends on !BR2_INSTALL_LIBSTDCPP || !BR2_TOOLCHAIN_HAS_THREADS || \
+		BR2_STATIC_LIBS
+	depends on BR2_PACKAGE_LIBOPENH264_ARCH_SUPPORTS
 
 config BR2_PACKAGE_GST1_PLUGINS_BAD_PLUGIN_OPENJPEG
 	bool "openjpeg"

package/gstreamer1/gst1-plugins-bad/gst1-plugins-bad.mk

@@ -714,6 +714,13 @@ else
 GST1_PLUGINS_BAD_CONF_OPTS += --disable-opencv
 endif
 
+ifeq ($(BR2_PACKAGE_GST1_PLUGINS_BAD_PLUGIN_OPENH264),y)
+GST1_PLUGINS_BAD_CONF_OPTS += --enable-openh264
+GST1_PLUGINS_BAD_DEPENDENCIES += libopenh264
+else
+GST1_PLUGINS_BAD_CONF_OPTS += --disable-openh264
+endif
+
 ifeq ($(BR2_PACKAGE_GST1_PLUGINS_BAD_PLUGIN_OPENJPEG),y)
 GST1_PLUGINS_BAD_CONF_OPTS += --enable-openjpeg
 GST1_PLUGINS_BAD_DEPENDENCIES += openjpeg