[build] Search for the git binary in the default msysgit install dir

core: Kill off type redefenitions in armdefs.h

The Git for Windows installer doesn't add the Git binaries to the path
by default. (Due to risk of conflicts with built-in windows commands.)
Unless you have configured your system specially this causes the
scm_rev_gen.js script to fail to find Git.  Added more paths to the
script so that it searches in the default msysgit installation
directory, eliminating the need to set the PATH for most environments.

BitField additions and fixes

Being able to store BitField within unions requires BitField to be of standard layout, which in turn is only given if the underlying type is also has standard layout.

Cf. https://github.com/dolphin-emu/dolphin/pull/483

Sometimes it can be beneficial to use this in places where an explicit cast needs to happen otherwise. By using the evaluation method, it's not necessary anymore to explicitly write the underlying type in this case.

Adds address arbiters to kernel HLE

AddressArbiter: Added documentation comment, fixed whitespace issue.

AddressArbiter: Fixed incorrect comment, reordered if-statement to be more clear.

SVC: Removed trailing whitespace.

Thread: Cleaned up arbitrate address functions.

Thread: Cleaned up ArbitrateAllThreads function.

Shared memory - adds preliminary support for shared memory kernel objects and correct block mapping.

- Also added some safety checks to MapSharedMemory.

- Previously, used a hard-coded shared memory handle of 0x10002000 (as used by libctru homebrew)

GSP: Added name for shared memory.

GSP: Cleaned up assertion message.

SharedMemory: Added optional name field for tracking known objects.

Adds preliminary RomFS archive support

- Required "file" handle to be made local and explicitly opened/closed as needed

Archive: Fixed brace ugliness for neobrain :)

FS: Commented out unused local variables to prevent warnings.

...But keeping them here for future use.

archive_romfs: Removed unused #include.

APT: More cleanups.

APT: Changed SignalType to be type u32.

NCCH: Removed extra qualification ‘Loader::AppLoader_NCCH::’.

FS: Added to CMakeLists.txt

Core: Updated CMakeLists.txt to remove directory_file_system and meta_file_system modules.

Refactor loader code and add preliminary NCCH support

NCCH: Updated LoadExec to use Memory::WriteBlock function to load binary code.