[indicator-session] dont patch tests/Makefile.am when not using tests

fixes:
    
    bp@bplap:~unity/Unity-for-Arch (git)-[master] % ./autoupdate.sh -Unyc 
    ==> resetting patches...
    ==> pulling from git...
    Already up-to-date.
    ==> applying patches...
    patching file compiz-ubuntu/PKGBUILD
    Hunk #1 succeeded at 104 (offset 16 lines).
    Hunk #2 succeeded at 114 with fuzz 2 (offset 15 lines).
    patching file indicator-session/PKGBUILD
    Hunk #1 succeeded at 56 (offset 22 lines).
    ==> building »indicator-session«
    ==> Making package: indicator-session 12.10.5daily13.06.19-100 (Mon Jun 24 18:43:39 CEST 2013)
    ==> Checking runtime dependencies...
    ==> Checking buildtime dependencies...
    ==> Retrieving sources...
      -> Found indicator-session_12.10.5daily13.06.19.orig.tar.gz
      -> Found translations-20130419-indicator-session.tar.gz
      -> Found 0001_Lock_Screen_Live_CD_Detection.patch
      -> Found 0002_There_is_no_help.patch
      -> Found 0003_Link_Against_pthread.patch
      -> Found 0004_Lock_Screen_Guest_Session_Detection.patch
    ==> Validating source files with sha512sums...
        indicator-session_12.10.5daily13.06.19.orig.tar.gz ... Passed
        translations-20130419-indicator-session.tar.gz ... Passed
        0001_Lock_Screen_Live_CD_Detection.patch ... Passed
        0002_There_is_no_help.patch ... Passed
        0003_Link_Against_pthread.patch ... Passed
        0004_Lock_Screen_Guest_Session_Detection.patch ... Passed
    ==> Extracting sources...
      -> Extracting indicator-session_12.10.5daily13.06.19.orig.tar.gz with bsdtar
      -> Extracting translations-20130419-indicator-session.tar.gz with bsdtar
    ==> Starting prepare()...
    patching file src/session-menu-mgr.c
    Hunk #2 succeeded at 1252 (offset -38 lines).
    patching file src/session-menu-mgr.c
    Hunk #1 succeeded at 429 (offset 49 lines).
    patching file tests/Makefile.am
    Hunk #1 FAILED at 40.
    1 out of 1 hunk FAILED -- saving rejects to file tests/Makefile.am.rej
    ==> ERROR: A failure occurred in prepare().
        Aborting...
    ~/devel/misc.arch/unity/Unity-for-Arch
    
    ==> done.
    skipped packages: 
    ignored packages: 
    failed  packages: ,indicator-session