Patch the gtk-doc makefiles so that the qemu wrapper is used to run transient
binaries instead of libtool wrapper or running them directly.

Also substitute a bogus plugin scanner, as trying to run the real one is causing
issues during build on x86_64.

Upstream-Status: Inappropriate
Signed-off-by: Ross Burton <ross.burton@intel.com>

--- a/common/gtk-doc.mak.orig	2017-12-20 12:43:20.586474397 +0000
+++ b/common/gtk-doc.mak	2017-12-20 12:45:20.758874995 +0000
@@ -8,3 +8,3 @@
 GTKDOC_LD = $(LIBTOOL) --tag=CC --mode=link $(CC) $(GTKDOC_DEPS_LIBS) $(AM_CFLAGS) $(CFLAGS) $(AM_LDFLAGS) $(LDFLAGS)
-GTKDOC_RUN = $(LIBTOOL) --mode=execute
+GTKDOC_RUN = $(top_builddir)/gtkdoc-qemuwrapper
 else
@@ -12,3 +12,3 @@
 GTKDOC_LD = $(CC) $(GTKDOC_DEPS_LIBS) $(AM_CFLAGS) $(CFLAGS) $(AM_LDFLAGS) $(LDFLAGS)
-GTKDOC_RUN =
+GTKDOC_RUN = $(top_builddir)/gtkdoc-qemuwrapper
 endif
@@ -99,2 +99,3 @@
 	    fi; \
+	    GST_PLUGIN_SCANNER_1_0="$(top_builddir)/libs/gst/helpers/gst-plugin-scanner-dummy" \
 	    GST_PLUGIN_SYSTEM_PATH_1_0=`cd $(top_builddir) && pwd`	\