[BUILD] Fix several minor LLVM build issues (#3202)

I'm not able to push LLVM binaries built from this branch to Azure
unfortunately, because it relies on branch filtered Entra ID now,
allowing only `llvm-head` and `main`. So I'll push it to main and then
update the storage from there.

.github/workflows/llvm-build.yml

@@ -27,7 +27,7 @@ jobs:
       matrix:
         config:
         - {runner: 'Ubuntu 20.04', runs_on: 'ubuntu-20.04', target-os: 'ubuntu', arch: 'x64'}
-        - {runner: 'Ubuntu 20.04', runs_on: 'ubuntu-20.04', target-os: 'ubuntu', arch: 'arm64'}
+        - {runner: 'Ubuntu 20.04 ARM64', runs_on: 'ubuntu-20.04', target-os: 'ubuntu', arch: 'arm64'}
         - {runner: 'CentOS 7', runs_on: ['self-hosted', 'CPU'], target-os: 'centos', arch: 'x64'}
         - {runner: 'MacOS X64', runs_on: 'macos-12', target-os: 'macos', arch: 'x64'}
         - {runner: 'MacOS ARM64', runs_on: 'macos-12', target-os: 'macos', arch: 'arm64'}
@@ -144,7 +144,7 @@ jobs:
         mkdir arm-sysroot
         mkdir -p llvm-project/host-tools
         cd llvm-project/host-tools
-        cmake -G Ninja ../llvm -G Ninja -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS="mlir;llvm;clang"
+        cmake -GNinja ../llvm -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS="mlir;llvm;clang"
         ninja mlir-tblgen
         ninja llvm-tblgen
         ninja clang-tblgen
@@ -205,6 +205,7 @@ jobs:
       if: matrix.config.arch == 'arm64' && matrix.config.target-os == 'macos'
       run: >
         python3 -m pip install -r llvm-project/mlir/python/requirements.txt
+
         cmake -GNinja -Bllvm-project/build
         -DCMAKE_BUILD_TYPE=Release
         -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++