[Patch v4] Add non-standard compiler prefix support

[Programmingkid]

This version of the patch reduces the for loop and comments' line length. 
It also has the loop test the CROSS_COMPILER variable first making things
a little more efficient.

Signed-off-by: John Arbuckle

Index: config/scripts/switch-arch
===================================================================
--- config/scripts/switch-arch	(revision 1335)
+++ config/scripts/switch-arch	(working copy)
@@ -99,7 +99,10 @@

select_prefix()
 {
-    for TARGET in ${1}-unknown-linux-gnu- ${1}-linux-gnu- ${1}-linux- ${1}-elf- ${1}-eabi-
+    # The user can specify the cross compiler like this: 
+    # CROSS_COMPILER=ppc-elf- ./switch-arch ppc
+    for TARGET in $CROSS_COMPILER ${1}-unknown-linux-gnu- ${1}-linux-gnu- \
+    ${1}-linux- ${1}-elf- ${1}-eabi-
     do
         if type ${TARGET}gcc > /dev/null 2>&1
         then