[virtcon] Don't update framebuffer with no display

This change reduces how much work the virtcon does when it doesn't have
ownership of the display. First, add checks for ownership to all checks
for the presence of a display (i.e. vc_gfx being non-null), so we treat
not having ownership the same as not having a framebuffer to render to.
Second, add ownership checks to all checks for vc->active, so we treat
not having ownership as all virtcons being inactive.

Test: Check that output during no display appears when focus is gained
Change-Id: Ib8ca77b0c9a104131bd37756878b30f7136c1b38

[syscalls] Change vmar..._old() calls back and use new params

ZX-2264
Test:CQ

Change-Id: If2a8635c6f1b53a942af3a8eaa2e82c25154ecdb

[virtcon] Avoid reading from WC memory

Reading from memory with a cache policy other than CACHED is
potentially very slow. Since gfx_surface needs to read from its buffer
for scrolling, if the framebuffer vmo can't be mapped CACHED then use a
second gfx_surface for rendering and blit the result to the framebuffer
vmo.

This change relies on the display driver setting an appropriate cache
policy with zx_set_cache_policy and keeping its own mapping of the VMO
to prevent the virtcon from setting the cache policy.

Bug: ZX-2198
Test: Check virtcon scrolling speed on NUC with intel_i915 disabled
Change-Id: I8af71b72ed9fff720947e685dee286d9c0edaf26

[syscalls] Change vmar_... calls

- Create zx_vm_option_t type
- Change ZX_VM_FLAG_... to ZX_VM_... and make them new type.
- Change int32_t flags parameters to zx_vm_option_t options
- Make the options parameter be second.

- Modify vmar_..._old functions to keep other repos working.
Once they've all been updated these functions will go away.

ZX-2264
Test:CQ

Change-Id: I1faf4cc4e1e4dabf3d8ef680e398d83a545b0f09

[virtcon] Migrate to new display APIs

Change-Id: Ia204796d3e52a7ca934fc171f4a231c89110dc1f

[virtcon] Add support for hotplugging

This change adds support for hotplugging to the virtcon. If multiple
displays are connected, the virtcon will use the display which was
attached first. The virtcon's contents and scrollback are kept when
switching between displays, although long lines will be truncated if
the virtcon moves to a smaller display.

When no display is connected, the console continues to function
normally, except without rendering anything. All checks for whether or
not any gfx operations should be done are in vc-device.

Change-Id: I467b9b1792f4d43803b521ec564dfe1873b85a97

Clean up sloppy zx_handle_t/integer conflation

Change-Id: I5659232efa8531ef97261639cc65f211ee9f0cc8

[zx] Magenta -> Zircon

The Great Renaming is here!

Change-Id: I3229bdeb2a3d0e40fb4db6fec8ca7d971fbffb94

[virtcon] Use the new MX_OK and MX_ERR_* mx_status_t names

Change-Id: I89dd39bd11d4d4b89321424cfc910b605688e307

[virtcon] cleanup

- remove some unused header includes
- remove unused vcdebug.h (xprintf was not used and now virtcon
filters its own debug prints out of the debug log console so
printf is safe to use if needed)
- clean up rules.mk to better reflect shared sources, libraries
- move shared code from main.cpp to vc-input.cpp
- no longer include main.cpp in virtual-console-test
- remove global lock, no longer needed in new single threaded design

Change-Id: I5aacc0f95f817f25ce96bbfa2f74d4877e9c4a16

[gfxconsole][virtcon] move and rename gfxconsole to virtcon

It's no longer a device, it's time for it to leave the
land of devices.

Change-Id: I977c56dbacb0794e6f67daac1dd6e3f4f2632f3d