[fzl] Clear free buffer list on re-init

Test: libfzl-test
Change-Id: I63c6d9533e8823942441e9d66bee7653bf8647b0

[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

[vmo-utils][fzl] Move contents of vmo-utils into fzl

Move copies of the vmo-centric helper classes which existed in
vmo-utils into fzl. This is step one of merging vmo-utils and libfzl.
Once higher level code has been migrated over to use the new library,
vmo-utils and its tests can be removed.

Also, merge the libfzl and fzl unit tests. I'm not sure how they got
divided in the first place, but now they are unified under just
libfzl.

ZX-2462 #comment Classes have been duplicated and added to libfzl
Test: Build and unit-test

Change-Id: Ie3bc07a9f78b6383032fcc974f28dd6af50caf21