Win32: Suppress an error message when baseruby is not found

Author: nobu

win32/Makefile.sub

@@ -23,10 +23,10 @@ MFLAGS=-l
 # executable in $(tooldir).
 ! if [cd $(tooldir) && ruby missing-baseruby.bat 2> nul]
 ! else if [(cd $(tooldir) && for %I in (ruby.exe) do @echo BASERUBY = %~s$$PATH:I) > baseruby.mk]
-! else
+! else if exist(baseruby.mk)
 !   include baseruby.mk
 ! endif
-! if [del baseruby.mk]
+! if [del baseruby.mk 2> nul]
 ! endif
 !else if "$(BASERUBY)" == "no" || [($(BASERUBY) -eexit) > nul 2> nul]
 BASERUBY =