Deb: build faster using ccache when available

debian/rules

@@ -59,7 +59,7 @@ ifneq ($(ARCH_OS),hurd)
 endif
 
 	( test -d $(builddir) || mkdir $(builddir) ) && cd $(builddir) && \
-	sh -c 'PATH=$${MYSQL_BUILD_PATH:-"/usr/local/bin:/usr/bin:/bin"} \
+	sh -c 'PATH=$${MYSQL_BUILD_PATH:-"/usr/lib/ccache:/usr/local/bin:/usr/bin:/bin"} \
 			CC=$${MYSQL_BUILD_CC:-gcc} \
 			CFLAGS=$${MYSQL_BUILD_CFLAGS:-"-O2 -fno-omit-frame-pointer -g -pipe -Wall -Wno-uninitialized"} \
 			CXX=$${MYSQL_BUILD_CXX:-g++} \