Update submodules

Publish Electron binaries for v5 only

Update frida-core

Update the Python dependencies hint in the README

Update submodules

Hack around frida-gadget initializer ordering

By playing with the linker's command-line and putting the entrypoint
object file last, we effectively make it so it will run _after_ V8's
initializer has been run. This is a terrible hack, but will have to do
until we find a better solution.

Bump SDK versions to 20190510

Only the Linux SDKs were rebuilt in order to apply Linux-specific fixes
to libffi.

Make the android-arm64 binaries smaller

By omitting the Capstone architecture support for 32-bit ARM when
building the 64-bit version. We only need this in the 64-bit build for
iOS, as it's used by frida-helper. This does however mean that the
frida-agent for ios-arm64 has 1 MB of unused bloat which we can get
rid of at some point.

Update frida-gum

Update frida-core