Add llvm installation for MacOS in install-gui.sh

[emlowe]

Purpose:

Current Behavior:

New Behavior:

Testing Notes:

[coveralls-official]

Pull Request Test Coverage Report for Build 17806332711

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 23 unchanged lines in 7 files lost coverage.
• Overall coverage decreased (-0.01%) to 91.15%

---

Files with Coverage Reduction	New Missed Lines	%
chia/full_node/full_node.py	1	87.27%
chia/_tests/simulation/test_simulation.py	1	96.47%
chia/wallet/wallet_node.py	1	87.05%
chia/timelord/timelord_launcher.py	2	89.29%
chia/util/files.py	2	91.38%
chia/server/address_manager.py	5	92.84%
chia/timelord/timelord.py	11	71.94%

Totals
Change from base Build 17773649562:	-0.01%
Covered Lines:	102727
Relevant Lines:	112539

---

💛 - Coveralls