[mm-common] Fix running doxygen when it is located at a path containing spaces (#630051)

[Armin Burgmeier <arminb src gnome org>]

commit 27f976e2a13dfbc75f106a371714790b626b2b9b
Author: Armin Burgmeier <armin arbur net>
Date:   Wed May 18 23:48:40 2011 +0200

    Fix running doxygen when it is located at a path containing spaces (#630051)

 build/doc-reference.am |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/build/doc-reference.am b/build/doc-reference.am
index c99ccc7..2c6a429 100644
--- a/build/doc-reference.am
+++ b/build/doc-reference.am
@@ -187,10 +187,12 @@ $(doc_outdir)/html/%: | $(doxytagfile)
 
 # Run Doxygen to build the reference documentation. The generated tag file
 # also functions as time stamp target for the documentation as a whole.
+# Quote $(DOXYGEN) so that this still works if this is a path containing
+# spaces such as "/c/Program Files (x86)/Doxygen/bin/doxygen"
 $(doxytagfile): $(doc_dependencies) | $(doc_config)
 	-$(AM_V_at)rm -f $@
 	-$(AM_V_at)rm -fr $(doc_outdir)/html
-	$(AM_V_GEN)(echo '@INCLUDE =' $(doc_config) && echo 'INPUT =' $(doc_input)) | $(DOXYGEN) -
+	$(AM_V_GEN)(echo '@INCLUDE =' $(doc_config) && echo 'INPUT =' $(doc_input)) | "$(DOXYGEN)" -
 	$(AM_V_at)$(doc_postprocess) '$(doc_outdir)/html/*.html'
 
 # Run XSL transformation to generate a Devhelp book from a Doxygen tag file.