Add gcc patch for multiarch support.

On Debian-based distributions,  gcc FTBFS because of special  linker files and
architecture-dependent  headers being  available in  /usr/lib/<triplet> rather
than /usr/lib  and /usr/lib64. This avoids  settings respectively LIBRARY_PATH
and CPATH manually on such distributions.

component/gcc/buildout.cfg

@@ -66,6 +66,13 @@ ignore-existing = true
 [gcc-java-source]
 location = ${buildout:parts-directory}/${:_buildout_section_name_}
 
+[gcc-multiarch.patch]
+recipe = hexagonit.recipe.download
+md5sum = 819e6735270c8a432b0512b49f40219f
+url = ${:_profile_base_location_}/${:filename}
+filename = ${:_buildout_section_name_}
+download-only = true
+
 [gcc-java]
 depends =
   ${gcc-download:location}
@@ -73,13 +80,15 @@ depends =
 recipe = hexagonit.recipe.cmmi
 path = ${gcc-java-source:location}
 md5sum = bb3265edf0fa7543e50cedb93e04e427
+patches =
+  ${gcc-multiarch.patch:location}/${gcc-multiarch.patch:filename}
+patch-options = -p2
 configure-command = make clean \\; make distclean \\; ./configure
 # GMP does not correctly detect achitecture so it have to be given
 # as hexagonit.recipe.cmmi is using shell expansion in subproceses
 # backticks are working
 configure-options =
   --disable-bootstrap
-  --build=`uname -m`-linux
   --enable-languages=java
   --disable-multilib
   --with-gmp=${gmp:location}