blfs tools: fix JOBS

If all cores are used, it should be set to 0, which will use nproc
after the cpuset has been defined, and not nproc (which is the number
of cores/threads on the machine).

common/libs/func_install_blfs

@@ -136,8 +136,9 @@ STATS=n
 SRC_ARCHIVE=/sources
 BUILD_ROOT=/sources
 BUILD_SUBDIRS=y
-JOBS=$(if [ "$ALL_CORES" = y ]; then nproc; else echo $N_PARALLEL; fi)
+JOBS=$(if [ "$ALL_CORES" = y ]; then echo 0; else echo $N_PARALLEL; fi)
 EOF
+# The 0 value above is for using all cores
 for OPT_VAR in CFLAGS CXXFLAGS LDFLAGS; do
   eval optVal=\$${OPT_VAR}_$DEF_OPT_MODE
   if [ -n "$optVal" ] && [ "$optVal" != unset ]; then