MJIT: Merge mjit_worker.c back to mjit.c (#6138)

Since #6006, we no longer avoid executing GC on mjit_worker.c and thus
there's no need to carefully change how we write code whether you're in
mjit.c or mjit_worker.c anymore.

common.mk

@@ -9658,7 +9658,6 @@ mjit.$(OBJEXT): {$(VPATH)}mjit.h
 mjit.$(OBJEXT): {$(VPATH)}mjit.rb
 mjit.$(OBJEXT): {$(VPATH)}mjit.rbinc
 mjit.$(OBJEXT): {$(VPATH)}mjit_config.h
-mjit.$(OBJEXT): {$(VPATH)}mjit_worker.c
 mjit.$(OBJEXT): {$(VPATH)}node.h
 mjit.$(OBJEXT): {$(VPATH)}onigmo.h
 mjit.$(OBJEXT): {$(VPATH)}oniguruma.h

test/ruby/test_mjit.rb

@@ -1228,7 +1228,7 @@ class TestMJIT < Test::Unit::TestCase
     success_actual = err.scan(/^#{JIT_SUCCESS_PREFIX}:/).size
     recompile_actual = err.scan(/^#{JIT_RECOMPILE_PREFIX}:/).size
     # Add --mjit-verbose=2 logs for cl.exe because compiler's error message is suppressed
-    # for cl.exe with --mjit-verbose=1. See `start_process` in mjit_worker.c.
+    # for cl.exe with --mjit-verbose=1. See `start_process` in mjit.c.
     if RUBY_PLATFORM.match?(/mswin/) && success_count != success_actual
       out2, err2 = eval_with_jit(script, verbose: 2, min_calls: min_calls, max_cache: max_cache)
     end