docs(README): update mac installation
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This clarifies the mac installation instructions.
---
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- [ ] `./mach build -d` does not report any errors
- [ ] `./mach test-tidy` does not report any errors
- [x] These changes fix#22905
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Update README instructions for Fedora, remove Ubuntu 14.04 workarounds
Fedora 31+ doesn't have python2-virtualenv, so using Python 3 with ```mach```
is required. Fedora 30 will be EOL within the next 6 weeks.
Ubuntu 14.04 is no longer receiving upstream support: https://www.omgubuntu.co.uk/2019/04/ubuntu-14-04-end-of-life
This is a follow up from 203a06ff24 (PR https://github.com/servo/servo/pull/24811/).
The old instructions lead to the following error:
```
$ brew bundle install --file=etc/taskcluster/macos/Brewfile-gstreamer
Error: No Brewfile found
```
Without LLVM installed you get: "Error: Can't find llvm-objdump" when
running ./mach build --dev
Signed-off-by: Jakob Sinclair <sinclair.jakob@mailbox.org>
* libunwind was required when building.
* Since Gentoo 17.1 the symlink between lib and lib64 has been removed.
- Update export so it works with both older and newer profiles.
Add `--build` and `--emulator-x86` to `./mach bootstrap-android`
This allows not downloading dependencies that are not needed for a particular task.
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