Implement long-since-promised video functions defined in
<syslinux/video.h>.  Use these functions in initvesa.c instead of
open-coding the same functionality.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Don't display the cursor on the graphical screen while doing a quiet
boot.  When doing a quiet boot we will probably show the graphical
screen for a fair bit of time; as a result, we really don't want a
completely bogus cursor blob on the bottom of the screen.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Make it possible to request nonstandard resolutions when enabling
vesacon.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

There are a fair number of valid JPEG images which we can validly
decode that aren't JFIF-complient, so don't require the JFIF header.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Impact: avoid kernel modules duplication

In modules.pcimap, kernel modules name are featuring '_' or '-' whereas modules.alias is only using '_'.
To avoid kernel modules duplication, let's rename all '-' by '_' to match what modules.alias provides
This avoid stupid duplications like "a-b" & "a_b" whereas they are in
fact the same kernel module

Impact: avoid code duplication

This will make code more generic, hdt will need it ;)

Close the file descriptor (freeing the file structure) when opening a
file fails.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Fix an uninitialized pointer bug; return void rather than returning
int like normal printfs... if we're depending on the return value of a
debugging function we're screwed when debugging is disabled.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>