Revert "util/abuild: Regenerate xcompile on every abuild run"

This reverts commit a2c009bd94.

Reason for revert: Breaks parallel abuilds.

Change-Id: I368b189050d519769f4852fea8e255e9b31b27b6
Signed-off-by: Reka Norman <rekanorman@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/57590
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>

util/abuild/abuild

@@ -788,7 +788,6 @@ fi
 
 # Generate a single xcompile for all boards
 export xcompile="${TARGET}/xcompile"
-rm -f "${xcompile}"
 $MAKE -C"${ROOT}" obj="$TARGET/temp" objutil="$TARGET/sharedutils" UPDATED_SUBMODULES=1 "${xcompile}" || exit 1
 
 customizing=$(echo "$customizing" | cut -c3-)