modesetting: Enable Xv when using glamor

This just calls the existing function to create the relevant Xv
adaptor and hook it up.

Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Move RTLD_DI_SETSIGNAL code into a separate block to quiet warning

Gets rid of gcc 4.8 warning:
 osinit.c:211:9: warning: ISO C90 forbids mixed declarations and code
  [-Wdeclaration-after-statement]

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
Solaris: Move shared declarations to xf86_OSlib.h

Gets rid of gcc 4.8 warnings:
 xf86AutoConfig.c:211:9: warning: nested extern declaration of
  'xf86SolarisFbDev' [-Wnested-externs]
 sun_VTsw.c:44:1: warning: no previous prototype for 'xf86VTRelease'
  [-Wmissing-prototypes]
 sun_VTsw.c:59:1: warning: no previous prototype for 'xf86VTAcquire'
  [-Wmissing-prototypes]

and ensures caller & definition stay in sync.

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Keith Packard <keithp@keithp.com>