harden build enviroment on mac with LODE

mac build really does not like finding extra stuff in the PATH
or in /usr/local/bin
as this is prone to happen with macport/fink/etc..
or somethings just due to some other 'ported to mac' pre-canned
binaries..
for instance one has found a python3 in /usr/local/bin
which confused configure to believe it was ok to use
'system python', which break on mac.

This patch sanitize PATH during ./autogen.sh, when running
in a LODE environment.
it leave only LODE_HOME/opt/bin:/usr/bin:/bin:/usr/sbin:/sbin  and optionally
the path where git is located if that is not /usr/bin
(it is quite common depending on how one installed git, to haev it in /usr/local/git/bin
for instance)

This is strictly a 'nanny' patch.. but it should not impact anyone
that is not ( on Mac and using LODE ).

Change-Id: I865047cfeb102ecb22777a1f7fb7cbdd374448aa
Reviewed-on: https://gerrit.libreoffice.org/16222
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Norbert Thiebaud <nthiebaud@gmail.com>
diff --git a/configure.ac b/configure.ac
index d214864..879b370 100644
--- a/configure.ac
+++ b/configure.ac
@@ -100,6 +100,26 @@ add_warning()
    echo "$COLORWARN $@" >> warn
}

dnl Some Mac User have the bad habbit of letting a lot fo crap
dnl accumulate in their PATH and even adding stuff in /usr/local/bin
dnl that confuse the build.
dnl For the ones that use LODE, let's be nice and protect them
dnl from themselves

mac_sanitize_path()
{
    mac_path="$LODE_HOME/opt/bin:/usr/bin:/bin:/usr/sbin:/sbin"
dnl a common but nevertheless necessary thing that may be in a fancy
dnl path location is git, so make sure we have it
    mac_git_path=`which git 2>/dev/null`
    if test -n "$mac_git_path" -a -x "$mac_git_path" -a "$mac_git_path" != "/usr/bin/git" ; then
        mac_path="$mac_path:`dirname $mac_git_path`"
    fi
    PATH="$mac_path"
    unset mac_path
    unset git_mac_path
}

echo "********************************************************************"
echo "*"
echo "*   Running ${PACKAGE_NAME} build configuration."
@@ -667,6 +687,10 @@ darwin*) # Mac OS X or iOS
        test_cups=no
    else
        _os=Darwin
        if test -n "$LODE_HOME" ; then
            mac_sanitize_path
            AC_MSG_NOTICE([sanitized the PATH to $PATH])
        fi
        INSTROOTSUFFIX=/$PRODUCTNAME.app/Contents
        SDKDIRNAME=AC_PACKAGE_NAME${PRODUCTVERSION}_SDK
    fi