i386.c (override_options): Respect user disable of fancy 387 math, sse, mmx.
* config/i386/i386.c (override_options): Respect user disable of
fancy 387 math, sse, mmx.
(construct_container): Generate error if we need an sse regster
and sse has been disabled.
* config/i386/i386.h (TARGET_SWITCHES): Disabling sse also disables
later sse generations. Disabling mmx also disables 3dnow.