build: cleanup: reformat AC_ARG_ENABLE

consistent use of tabs/non-tabs.

consistent use of formatting method for all statements.

consistent indent, single tab, not "drawing" code.

shorter lines as requested.

Change-Id: I105c03e374d9f63017b50444c3f8e1cb17e75b37
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>
Signed-off-by: Dan Kenigsberg <danken@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/18939
Reviewed-by: Zhou Zheng Sheng <zhshzhou@linux.vnet.ibm.com>