utils: silence g-ir-scanner warnings about float conversion macros

utils: silence g-ir-scanner warnings about float conversion macros

663: Warning: Gst: symbol='GFLOAT_TO_LE': Unknown namespace for symbol 'GFLOAT_TO_LE'
664: Warning: Gst: symbol='GFLOAT_TO_BE': Unknown namespace for symbol 'GFLOAT_TO_BE'
665: Warning: Gst: symbol='GDOUBLE_TO_LE': Unknown namespace for symbol 'GDOUBLE_TO_LE'
666: Warning: Gst: symbol='GDOUBLE_TO_BE': Unknown namespace for symbol 'GDOUBLE_TO_BE'
669: Warning: Gst: symbol='GFLOAT_TO_LE': Unknown namespace for symbol 'GFLOAT_TO_LE'
670: Warning: Gst: symbol='GFLOAT_TO_BE': Unknown namespace for symbol 'GFLOAT_TO_BE'
671: Warning: Gst: symbol='GDOUBLE_TO_LE': Unknown namespace for symbol 'GDOUBLE_TO_LE'
672: Warning: Gst: symbol='GDOUBLE_TO_BE': Unknown namespace for symbol 'GDOUBLE_TO_BE'
678: Warning: Gst: symbol='GFLOAT_FROM_LE': Unknown namespace for symbol 'GFLOAT_FROM_LE'
679: Warning: Gst: symbol='GFLOAT_FROM_BE': Unknown namespace for symbol 'GFLOAT_FROM_BE'
680: Warning: Gst: symbol='GDOUBLE_FROM_LE': Unknown namespace for symbol 'GDOUBLE_FROM_LE'
681: Warning: Gst: symbol='GDOUBLE_FROM_BE': Unknown namespace for symbol 'GDOUBLE_FROM_BE'

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/579>