Fixing build error:

/run/build/gst-plugins-good/_flatpak_build/../tests/check/elements/mpg123audiodec.c:150: undefined reference to `gst_fft_s32_new'
/run/build/gst-plugins-good/_flatpak_build/../tests/check/elements/mpg123audiodec.c:151: undefined reference to `gst_fft_s32_window'
/run/build/gst-plugins-good/_flatpak_build/../tests/check/elements/mpg123audiodec.c:151: undefined reference to `gst_fft_s32_fft'
/run/build/gst-plugins-good/_flatpak_build/../tests/check/elements/mpg123audiodec.c:147: undefined reference to `gst_fft_s32_free'