build: fix native_mksnapshot magic number mismatch (3-0-x)

[jkleinsc]

Description of Change

This PR fixes electron/electron#15312 for 3-0-x. Setting v8_enable_i18n_support = false was causing the following error when using snapshots generated from arm/arm64 native mksnapshot binaries:

#
# Fatal error in ../../v8/src/snapshot/deserializer.cc, line 79
# Check failed: magic_number_ == SerializedData::ComputeMagicNumber(external_reference_table_).
#
Illegal instruction

v8_enable_i18n_support = false was originally set to false because when we added native mksnapshot binaries for arm in 1-8-x running those binaries caused an error about a missing shared library, libicui18n.so. However in setting this flag to false the snapshots generated have a non matching magic number to what Electron expects because Electron is (and should be) built with v8_enable_i18n_support = true. In 3-0-x the libicui18n.so issue doesn't exist, so its safe to change this flag.

Checklist

• [x] PR description included and stakeholders cc'd
• [x] script/update runs without error
• [x] PR title follows semantic commit guidelines

[deepak1556]

@jkleinsc can you also fix this in libcc 3-1-x branch, thanks!

[jkleinsc]

/trop run backport-to electron-3-1-x

[trop[bot]]

The backport process for this PR has been manually initiated, sending your 1's and 0's to "electron-3-1-x" here we go! :D

[trop[bot]]

I have automatically backported this PR to "electron-3-1-x", please check out #732