global: do not offer the renice option, let's the user handle that

It's broken anyway. Eg.:
- user is already niced at 10
- user configures to renice at 5
- breaks because user is not allowed to 'boost' his/her nice value

Bette let the user handle the renice with:
  nice -XX ct-ng 'action'

config/global/build-behave.in

@@ -28,14 +28,6 @@ config LOAD
       Note: only the integer part of the load is allowed here (you can't enter
             0.75 for example).
 
-config NICE
-    int
-    prompt "Nice level"
-    default 0
-    range 0 19
-    help
-      Renices the build process up.
-
 config USE_PIPES
     bool
     prompt "Use -pipe"

scripts/crosstool-NG.sh.in

@@ -97,9 +97,6 @@ CT_STAR_DATE_HUMAN=$(CT_DoDate +%Y%m%d.%H%M%S)
 # Log real begining of build, now
 CT_DoLog INFO "Build started ${CT_STAR_DATE_HUMAN}"
 
-# renice oursleves
-CT_DoExecLog DEBUG renice ${CT_NICE} $$
-
 CT_DoStep DEBUG "Dumping user-supplied crosstool-NG configuration"
 CT_DoExecLog DEBUG grep -E '^(# |)CT_' .config
 CT_EndStep