strip ccache from CC and CXX from rbconfig.rb
as a side effect, we need to pass CC to sub-makes

--- ruby-2.0.0-p353/tool/mkconfig.rb~	2013-03-24 17:42:06.000000000 +0200
+++ ruby-2.0.0-p353/tool/mkconfig.rb	2014-03-18 10:34:08.489251715 +0200
@@ -77,6 +77,7 @@
     when /^(?:MAJOR|MINOR|TEENY)$/; next
     when /^RUBY_INSTALL_NAME$/; next if $install_name
     when /^RUBY_SO_NAME$/; next if $so_name
+    when /^(CC|CXX)$/; val.sub!(/ccache /, '')
     when /^arch$/; if val.empty? then val = arch else arch = val end
     when /^sitearch$/; val = '$(arch)' if val.empty?
     end
--- ruby-2.0.0-p451/common.mk	2014-04-05 16:16:52.983112032 +0300
+++ ruby-2.0.0-p451/common.mk	2014-04-05 16:26:58.679843426 +0300
@@ -176,7 +176,7 @@
 configure-ext: $(EXTS_MK)
 
 build-ext: $(EXTS_MK)
-	$(Q)$(MAKE) -f $(EXTS_MK) $(MFLAGS) $(EXTSTATIC) LIBRUBY_EXTS=$(LIBRUBY_EXTS) ENCOBJS="$(ENCOBJS)"
+	$(Q)$(MAKE) -f $(EXTS_MK) $(MFLAGS) $(EXTSTATIC) LIBRUBY_EXTS=$(LIBRUBY_EXTS) ENCOBJS="$(ENCOBJS)" CC="$(CC)"
 
 $(MKMAIN_CMD): $(MKFILES) all-incs $(PREP) $(RBCONFIG) $(LIBRUBY)
 	$(Q)$(MINIRUBY) $(srcdir)/ext/extmk.rb --make="$(MAKE)" --command-output=$@ $(EXTMK_ARGS)
@@ -545,7 +545,7 @@
 	$(ECHO) making $@
 	$(Q) $(MAKE) -f $(ENC_MK) V="$(V)" \
 		RUBY="$(MINIRUBY)" MINIRUBY="$(MINIRUBY)" \
-		$(MFLAGS) $@
+		$(MFLAGS) CC="$(CC)" $@
 
 
 libenc enc: {$(VPATH)}encdb.h
@@ -860,7 +860,7 @@
 
 srcs-enc: $(ENC_MK)
 	$(ECHO) making srcs under enc
-	$(Q) $(MAKE) -f $(ENC_MK) RUBY="$(MINIRUBY)" MINIRUBY="$(MINIRUBY)" $(MFLAGS) srcs
+	$(Q) $(MAKE) -f $(ENC_MK) RUBY="$(MINIRUBY)" MINIRUBY="$(MINIRUBY)" CC="$(CC)" $(MFLAGS) srcs
 
 all-incs: incs
 incs: $(INSNS) {$(VPATH)}node_name.inc {$(VPATH)}encdb.h {$(VPATH)}transdb.h {$(VPATH)}known_errors.inc \