Bug 243665 Use sensible default install location (instead of .)

patch by ajschult@verizon.net r=bryner

browser/installer/unix/config.it

@@ -20,6 +20,7 @@ User Agent=$UserAgent$
 ;   WINDIR
 ;   WINSYSDIR
 Path=[PROGRAMFILESDIR]\$ProductName$
+Default Location=/usr/local/$MainExeFile$
 
 ; Sub Path, when set will indicate to Setup to create a subfolder from
 ; what is offered to the user to change.  It will not be shown to the user