This fixes the following warnings:

    src/libtracker-miner/Makefile-shared-sources.decl:5: warning: source file '$(top_srcdir)/src/libtracker-miner/tracker-monitor.c' is in a subdirectory,
    src/libtracker-miner/Makefile-shared-sources.decl:5: but option 'subdir-objects' is disabled
    src/libtracker-miner/Makefile.am:10:   'src/libtracker-miner/Makefile-shared-sources.decl' included from here
    automake: warning: possible forward-incompatibility.
    automake: At least a source file is in a subdirectory, but the 'subdir-objects'
    automake: automake option hasn't been enabled.  For now, the corresponding output
    automake: object file(s) will be placed in the top-level directory.  However,
    automake: this behaviour will change in future Automake versions: they will
    automake: unconditionally cause object files to be placed in the same subdirectory
    automake: of the corresponding sources.
    automake: You are advised to start using 'subdir-objects' option throughout your
    automake: project, to avoid future incompatibilities.
    src/tracker-preferences/Makefile.am:34: warning: source file '$(top_srcdir)/src/miners/fs/tracker-config.c' is in a subdirectory,
    src/tracker-preferences/Makefile.am:34: but option 'subdir-objects' is disabled
    src/libtracker-miner/Makefile-shared-sources.decl:17: warning: source file '$(top_srcdir)/src/libtracker-miner/tracker-crawler.c' is in a subdirectory,
    src/libtracker-miner/Makefile-shared-sources.decl:17: but option 'subdir-objects' is disabled
    tests/libtracker-miner/Makefile.am:11:   'src/libtracker-miner/Makefile-shared-sources.decl' included from here
    src/libtracker-miner/Makefile-shared-sources.decl:5: warning: source file '$(top_srcdir)/src/libtracker-miner/tracker-monitor.c' is in a subdirectory,
    src/libtracker-miner/Makefile-shared-sources.decl:5: but option 'subdir-objects' is disabled
    tests/libtracker-miner/Makefile.am:11:   'src/libtracker-miner/Makefile-shared-sources.decl' included from here
    autoreconf: automake failed with exit status: 1