Fix pjproject compilation in certain circumstances

On a fresh checkout of Asterisk 11, running make before ./configure
could cause the pjproject subdirectory to get in an odd state that
would prevent compilation. This patch by Tilghman prevents that from
occurring.

(closes issue ASTERISK-20681)
Patch-by: Tilghman Lesher
........

Merged revisions 378582 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@378585 f38db490-d61c-443f-a65b-d21fe96a405b