This patch fixes a bug in guile-rsvg's build system, whereby the CFLAGS
and LDFLAGS for Guile would not be captured.

--- guile-rsvg-2.18.1/configure.ac	2015-08-31 22:30:30.578909480 +0200
+++ guile-rsvg-2.18.1/configure.ac	2015-08-31 22:32:15.071516084 +0200
@@ -39,6 +39,10 @@ AC_SUBST(WARN_CFLAGS)
 
 GUILE_PKG([2.2 2.0 1.8])
 
+dnl The above macro fails to set the 'GUILE_CFLAGS' and 'GUILE_LIBS'
+dnl substitution variables, hence this line.
+PKG_CHECK_MODULES(GUILE, guile-$GUILE_EFFECTIVE_VERSION)
+
 PKG_CHECK_MODULES(GUILE_CAIRO, guile-cairo >= 1.4.0)
 AC_SUBST(GUILE_CAIRO_LIBS)
 AC_SUBST(GUILE_CAIRO_CFLAGS)