- flesh out helptext of DOMULTI.

  Put short, just leave it alone or keep all parts --
  alternatively go help with lto if you have time.

extra/Configs/Config.in

@@ -1957,6 +1957,13 @@ config DOMULTI
 	default n
 	help
 	  Set this to compile all sources at once into an object (IMA).
+	  This mode of compilation uses alot of memory but may produce
+	  smaller binaries.
+
+	  Note that you need a very recent GCC for this to work, like
+	  gcc >= 4.3 plus eventually some patches.
+
+	  If unsure, keep the default of N.
 
 config UCLIBC_MJN3_ONLY
 	bool "Manuel's hidden warnings"