Force /bin/echo in git section

Apple's version of bash version 3, when called as /bin/sh, uses an internal echo command which doesn't handle the "-n" argument and contaminates the git version string. /bin/echo correctly handles the -n argument.

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@20654 57a11ea4-9604-0410-9ed3-97b8803252fd

util/gnc-svnversion

@@ -69,12 +69,12 @@ if test -d "${real_gitdir}"
 then
   githead=`git --git-dir "${real_gitdir}" log -1 --pretty=format:"%h" HEAD 2>/dev/null`  # short hash only
   if test $? = 0 ; then
-    echo -n $githead
+    /bin/echo -n $githead
     # Add a "+" to the hash if there deleted or modified files (not excluded by .gitignore and friends)
     # "Ignores" untracked files
-    # [ $(git --git-dir "${real_gitdir}" ls-files -dkm 2>/dev/null | wc -l) -gt 0 ] && echo -n "+"
+    # [ $(git --git-dir "${real_gitdir}" ls-files -dkm 2>/dev/null | wc -l) -gt 0 ] && /bin/echo -n "+"
     # Includes untracked files
-    [ $(git --git-dir "${real_gitdir}" ls-files -dkmo --exclude-standard 2>/dev/null | wc -l) -gt 0 ] && echo -n "+"
+    [ $(git --git-dir "${real_gitdir}" ls-files -dkmo --exclude-standard 2>/dev/null | wc -l) -gt 0 ] && /bin/echo -n "+"
     echo
     exit 0
   else