It looks like I need to build mpfr. The gmp(-native) and and mpfr(-native)
situation in the -cross-sdk files is interesting as sometimes we don't need them
sometimes we do...
--- /dev/null
+DESCRIPTION = "The GNU cc and gcc C compilers."
+HOMEPAGE = "http://www.gnu.org/software/gcc/"
+SECTION = "devel"
+LICENSE = "GPL"
+PR = "r2"
+
+inherit sdk
+
+FILESDIR = "${@os.path.dirname(bb.data.getVar('FILE',d,1))}/gcc-${PV}"
+
+DEPENDS = "virtual/${TARGET_PREFIX}binutils virtual/${TARGET_PREFIX}libc-for-gcc mpfr"
+PACKAGES = "${PN}"
+
+require gcc_${PV}.bb
+require gcc4-build-sdk.inc
+require gcc-package-sdk.inc