Remove never used macros related to RJIT [ci skip]

These macros have not been used since the commit "Stop exporting
symbols for MJIT" 233ddfac54, and
renamed as RJIT.

common.mk

@@ -471,8 +471,6 @@ ruby.imp: $(COMMONOBJS)
 	$(Q){ \
 	$(NM) -Pgp $(COMMONOBJS) | \
 	awk 'BEGIN{print "#!"}; $$2~/^[A-TV-Z]$$/&&$$1!~/^$(SYMBOL_PREFIX)(Init_|InitVM_|ruby_static_id_|.*_threadptr_|rb_ec_)|^\./{print $$1}'; \
-	($(CHDIR) $(srcdir) && \
-	 exec sed -n '/^RJIT_FUNC_EXPORTED/!d;N;s/.*\n\(rb_[a-zA-Z_0-9]*\).*/$(SYMBOL_PREFIX)\1/p' cont.c gc.c thread*c vm*.c) \
 	} | \
 	sort -u -o $@
 

template/Doxyfile.tmpl

@@ -2359,10 +2359,6 @@ PREDEFINED            += DEPRECATED(_)=_
 PREDEFINED            += DEPRECATED_BY(__,_)=_
 PREDEFINED            += ENUM_OVER_INT=1
 PREDEFINED            += ERRORFUNC(__,_)=_
-PREDEFINED            += RJIT_FUNC_EXPORTED=
-PREDEFINED            += RJIT_STATIC=extern
-PREDEFINED            += RJIT_SYMBOL_EXPORT_BEGIN=
-PREDEFINED            += RJIT_SYMBOL_EXPORT_END=
 PREDEFINED            += NOINLINE(_)=_
 PREDEFINED            += NORETURN(_)=_
 PREDEFINED            += PACKED_STRUCT_UNALIGNED(_)=_