[NFC][CMake] quote ${CMAKE_SYSTEM_NAME} consistently (#154537)
A CMake change included in CMake 4.0 makes `AIX` into a variable
(similar to `APPLE`, etc.)
https://gitlab.kitware.com/cmake/cmake/-/commit/ff03db6657c38c8cf992877ea66174c33d0bcb0b
However, `${CMAKE_SYSTEM_NAME}` unfortunately also expands exactly to
`AIX` and `if` auto-expands variable names in CMake. That means you get
a double expansion if you write:
`if (${CMAKE_SYSTEM_NAME} MATCHES "AIX")`
which becomes:
`if (AIX MATCHES "AIX")`
which is as if you wrote:
`if (ON MATCHES "AIX")`
You can prevent this by quoting the expansion of "${CMAKE_SYSTEM_NAME}",
due to policy
[CMP0054](https://cmake.org/cmake/help/latest/policy/CMP0054.html#policy:CMP0054)
which is on by default in 4.0+. Most of the LLVM CMake already does
this, but this PR fixes the remaining cases where we do not.
GitOrigin-RevId: 63195d3d7a8bde05590f91a38398f986bb4265b2
2 files changed
