mkenv: Move away from clang

It was nice, but it isn't as good at cross-compiling yet.  Plus, by sticking
with gcc, we have one compiler throughout the entire system.

Signed-off-by: Sean Cross <xobs@kosagi.com>

Author: Sean Cross

mkenv.mk

@@ -44,12 +44,14 @@ SED = sed
 PYTHON = python
 
 AS = $(CROSS_COMPILE)gcc $(CFLAGS) -D__ASSEMBLY__
-CC = $(CROSS_COMPILE)clang
+CC = $(CROSS_COMPILE)gcc
 LD = $(CROSS_COMPILE)ld
 OBJCOPY = $(CROSS_COMPILE)objcopy
 SIZE = $(CROSS_COMPILE)size
 STRIP = $(CROSS_COMPILE)strip
 
+CC_NATIVE ?= gcc
+
 all:
 .PHONY: all