CMake: disable deprecated function warnings

LLVM 14 deprecated a bunch of C API functions in preparation for opaque
pointer changes. However, they did not actually implement opaque pointer
semantics, so the deprecations are largely masturbatory. I have nothing
against masturbation, I am just busy trying to get the self hosted
compiler done for 0.10.0, so we will come back to this later.

Author: andrewrk

CMakeLists.txt

@@ -854,7 +854,7 @@ endif()
 if(MSVC)
     set(EXE_CFLAGS "${EXE_CFLAGS}")
 else()
-    set(EXE_CFLAGS "${EXE_CFLAGS} -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -D_GNU_SOURCE -fvisibility-inlines-hidden -fno-exceptions -fno-rtti -Werror=type-limits -Wno-missing-braces -Wno-comment")
+    set(EXE_CFLAGS "${EXE_CFLAGS} -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -D_GNU_SOURCE -fvisibility-inlines-hidden -fno-exceptions -fno-rtti -Werror=type-limits -Wno-missing-braces -Wno-comment -Wno-deprecated-declarations")
     if(MINGW)
         set(EXE_CFLAGS "${EXE_CFLAGS} -Wno-format")
     endif()