diff -r c004067a7b34 config.sh
--- a/config.sh	Sun Oct 02 20:51:04 2016 -0400
+++ b/config.sh	Fri Jan 27 17:47:25 2017 -0500
@@ -1,13 +1,15 @@
 # ARCH will be auto-detected as the host if not specified
 #ARCH=i486
-#ARCH=x86_64
+ARCH=x86_64
 #ARCH=powerpc
 #ARCH=arm
 #ARCH=microblaze
 #ARCH=mips
 #ARCH=mipsel
 
-CC_BASE_PREFIX=/opt/cross
+if [ -z "$CC_BASE_PREFIX" ]; then
+	CC_BASE_PREFIX=$HOME/heads/install
+fi
 
 # If you use arm, you may need more fine-tuning:
 # arm hardfloat v7
@@ -24,3 +26,6 @@
 
 # Enable this to build the bootstrap gcc (thrown away) without optimization, to reduce build time
 GCC_STAGE1_NOOPT=1
+
+# Build GMP, MPFR and MPC
+GCC_BUILTIN_PREREQS=yes