[flang] [llvm] [CMake] Fix using precompiled headers with ccache (PR #131397)

[Kajetan Puchalski via llvm-commits]

================
@@ -291,7 +291,7 @@ if(LLVM_CCACHE_BUILD)
       set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE ${CCACHE_PROGRAM})
     else()
       if(LLVM_CCACHE_MAXSIZE OR LLVM_CCACHE_DIR OR
-         NOT LLVM_CCACHE_PARAMS MATCHES "CCACHE_CPP2=yes CCACHE_HASHDIR=yes")
+         NOT LLVM_CCACHE_PARAMS MATCHES "CCACHE_CPP2=yes CCACHE_HASHDIR=yes CCACHE_SLOPPINESS=pch_defines,time_macros")
----------------
mrkajetanp wrote:

Ah ok, we just need to be careful with the quoting. This works:
```
+    set(launcher ${CMAKE_COMMAND} -E env ${launcher_env} ${CCACHE_PROGRAM})
+    set(CMAKE_C_COMPILER_LAUNCHER ${launcher})
+    set(CMAKE_CXX_COMPILER_LAUNCHER ${launcher})
```

https://github.com/llvm/llvm-project/pull/131397