posix compatibility: avoid grep GNU extension (JuliaLang#53400)

the `.\+` meta-character is a GNU extension. prefer to use the POSIX
equivalent `..*` to work with `grep` on wider platforms.

it is part of on-going work to port julia to OpenBSD.

src/Makefile

@@ -230,7 +230,7 @@ $(BUILDDIR)/jl_internal_funcs.inc: $(SRCDIR)/jl_exported_funcs.inc
 	# to have a `ijl_` prefix instead of `jl_`, to denote that they are coming from `libjulia-internal`.  This avoids
 	# potential confusion with debugging tools, when inspecting a process that has both `libjulia` and `libjulia-internal`
 	# loaded at the same time.
-	grep 'XX(.\+)' $< | sed -E 's/.*XX\((.+)\).*/#define \1 i\1/g' >$@
+	grep 'XX(..*)' $< | sed -E 's/.*XX\((.+)\).*/#define \1 i\1/g' >$@
 
 # source file rules
 $(BUILDDIR)/%.o: $(SRCDIR)/%.c $(HEADERS) | $(BUILDDIR)