AUTOMOC: Avoid compiler warnings while computing predefines

LLVM/Clang 20, when invoked as `clang++ -E -c ...`, now warns:

    warning: argument unused during compilation: '-c'

Drop the unnecessary `-c` flag.  Also add a `-w` flag to suppress
warnings so their text is not parsed as predefines.

Modules/Compiler/GNU.cmake

@@ -133,7 +133,7 @@ macro(__compiler_gnu lang)
       list(APPEND CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND ${_COMPILER_ARGS})
       unset(_COMPILER_ARGS)
     endif()
-    list(APPEND CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND "-dM" "-E" "-c" "${CMAKE_ROOT}/Modules/CMakeCXXCompilerABI.cpp")
+    list(APPEND CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND "-w" "-dM" "-E" "${CMAKE_ROOT}/Modules/CMakeCXXCompilerABI.cpp")
   endif()
 
   if(NOT "x${lang}" STREQUAL "xFortran")

Modules/Compiler/IBMClang.cmake

@@ -70,7 +70,7 @@ macro(__compiler_ibmclang lang)
   )
 
   if("${lang}" STREQUAL "CXX")
-    list(APPEND CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND "-dM" "-E" "-c" "${CMAKE_ROOT}/Modules/CMakeCXXCompilerABI.cpp")
+    list(APPEND CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND "-w" "-dM" "-E" "${CMAKE_ROOT}/Modules/CMakeCXXCompilerABI.cpp")
   endif()
 
   set(CMAKE_PCH_EXTENSION .pch)

Modules/Compiler/Intel.cmake

@@ -40,7 +40,7 @@ else()
         list(APPEND CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND ${_COMPILER_ARGS})
         unset(_COMPILER_ARGS)
       endif()
-      list(APPEND CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND "-QdM" "-P" "-Za" "${CMAKE_ROOT}/Modules/CMakeCXXCompilerABI.cpp")
+      list(APPEND CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND "-w" "-QdM" "-P" "-Za" "${CMAKE_ROOT}/Modules/CMakeCXXCompilerABI.cpp")
     endif()
 
     if("x${lang}" STREQUAL "xFortran")

Modules/Compiler/IntelLLVM.cmake

@@ -100,7 +100,7 @@ else()
         list(APPEND CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND ${_COMPILER_ARGS})
         unset(_COMPILER_ARGS)
       endif()
-      list(APPEND CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND "-dM" "-E" "-c" "${CMAKE_ROOT}/Modules/CMakeCXXCompilerABI.cpp")
+      list(APPEND CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND "-w" "-dM" "-E" "${CMAKE_ROOT}/Modules/CMakeCXXCompilerABI.cpp")
       if(CMAKE_${lang}_COMPILER_TARGET)
         list(APPEND CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND "--target=${CMAKE_${lang}_COMPILER_TARGET}")
       endif()

Modules/Compiler/LCC.cmake

@@ -83,7 +83,7 @@ macro(__compiler_lcc lang)
       list(APPEND CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND ${_COMPILER_ARGS})
       unset(_COMPILER_ARGS)
     endif()
-    list(APPEND CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND "-dM" "-E" "-c" "${CMAKE_ROOT}/Modules/CMakeCXXCompilerABI.cpp")
+    list(APPEND CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND "-w" "-dM" "-E" "${CMAKE_ROOT}/Modules/CMakeCXXCompilerABI.cpp")
   endif()
 
   if(NOT "x${lang}" STREQUAL "xFortran")