linux build: let's be clear that 64 bit is not supported

* rename the cmake option to 64BIT_BUILD_DONT_WORK
* add --64-bit-dont-work to build.sh

build.sh

@@ -36,6 +36,7 @@ for ARG in "$@"; do
         --asan        ) flags+=(-DUSE_ASAN=TRUE) ;;
         --wx28        ) flags+=(-DWX28_API=TRUE) ;;
         --wx30        ) flags+=(-DWX28_API=FALSE) ;;
+        --64-bit-dont-work ) flags+=(-D64_BIT_BUILD_DONT_WORK=TRUE) ;;
 
         *)
             # Unknown option
@@ -55,6 +56,8 @@ for ARG in "$@"; do
             echo "--egl           : Replace GLX by EGL (ZZogl plugins only)"
             echo "--sdl2          : Build with SDL2 (crash if wx is linked to SDL1)"
             echo "--gles          : Replace openGL backend of GSdx by openGLES3"
+            echo
+            echo "--64-bit-dont-work : Don't use it!"
             exit 1
     esac
 done

cmake/BuildParameters.cmake

@@ -59,7 +59,7 @@ option(USE_ASAN "Enable address sanitizer")
 #-------------------------------------------------------------------------------
 # Select the architecture
 #-------------------------------------------------------------------------------
-option(64BIT_BUILD "Enable a x86_64 build instead of cross compiling (developer option)" OFF)
+option(64BIT_BUILD_DONT_WORK "Enable a x86_64 build instead of cross compiling (WARNING: NOTHING WORK)" OFF)
 
 # Architecture bitness detection
 if(CMAKE_SIZEOF_VOID_P EQUAL 8)
@@ -71,7 +71,7 @@ endif()
 # Print a clear message that 64bits is not supported
 if(_ARCH_64)
     message(WARNING "
-    PCSX2 does not support a 64-bits environment and has no plan to support a 64-bits architecture in the future.
+    PCSX2 does not support a 64-bits environment and has no yet a plan to support it.
     It would need a complete rewrite of the core emulator and a lot of time.
 
     You can still run a 32-bits binary if you install all 32-bits libraries (runtime and dev).")