postprocess-asm rule doesn't respect RUBY_EXECUTABLE

https://bugs.webkit.org/show_bug.cgi?id=254965

Reviewed by Yusuke Suzuki.

postprocess-asm is a Ruby script with #/!/usr/bin/env ruby as its shebang which
looks up Ruby in PATH. webkit, however, has RUBY_EXECUTABLE as a CMake option.
It's possible for the Ruby used by CMake (and the other rules during the build)
to be different to the first Ruby found in PATH. This makes the usage for postprocess-asm
consistent with other uses in webkit.

* Source/JavaScriptCore/CMakeLists.txt

Canonical link: https://commits.webkit.org/262719@main

Source/JavaScriptCore/CMakeLists.txt

@@ -1507,7 +1507,7 @@ endif ()
 if (CMAKE_COMPILER_IS_GNUCXX AND GCC_OFFLINEASM_SOURCE_MAP)
     message(STATUS "Enabling asm postprocessing")
 
-    set(LowLevelInterpreter_LAUNCHER "${JavaScriptCore_SCRIPTS_SOURCES_DIR}/postprocess-asm")
+    set(LowLevelInterpreter_LAUNCHER "${RUBY_EXECUTABLE} ${JavaScriptCore_SCRIPTS_SOURCES_DIR}/postprocess-asm")
     get_target_property(PROP_RULE_LAUNCH_COMPILE LowLevelInterpreterLib RULE_LAUNCH_COMPILE)
     if (PROP_RULE_LAUNCH_COMPILE)
         set(LowLevelInterpreter_LAUNCHER "${LowLevelInterpreter_LAUNCHER} ${PROP_RULE_LAUNCH_COMPILE}")