patch 8.2.2241: Build with Ruby and clang may fail

Problem:    Build with Ruby and clang may fail.
Solution:   Adjust congigure and sed script. (Ozaki Kiichi, closes #7566)

src/configure.ac

@@ -2001,6 +2001,9 @@ if test "$enable_rubyinterp" = "yes" -o "$enable_rubyinterp" = "dynamic"; then
 	  RUBY_CFLAGS="-DDYNAMIC_RUBY_DLL=\\\"$libruby_soname\\\" $RUBY_CFLAGS"
 	  RUBY_LIBS=
 	fi
+	if test "X$CLANG_VERSION" != "X" -a "$rubyversion" -ge 30; then
+	  RUBY_CFLAGS="$RUBY_CFLAGS -fdeclspec"
+	fi
       else
 	AC_MSG_RESULT(not found; disabling Ruby)
       fi