libc/uClibc: Add CUSTOM version and CUSTOM_LOCATION config options and GetCustom

CUSTOM_LOCATION config options only presented in menuconfig if component
CUSTOM version selected.

Signed-off-by: "David Holsgrove" <david.holsgrove@xilinx.com>
[yann.morin.1998@free.fr: fix indentation, don't patch custom dir location]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Message-Id: <712995e3e719fbbe24af.1349931201@localhost.localdomain>
PatchWork-Id: 190794

 diff -durN gcc-4.4.0.orig/libgomp/configure gcc-4.4.0/libgomp/configure

 --- gcc-4.4.0.orig/libgomp/configure	2009-04-21 11:08:08.000000000 +0200

 +++ gcc-4.4.0/libgomp/configure	2009-05-27 21:38:19.000000000 +0200

 @@ -3334,7 +3334,7 @@

  # Add -Wall -Werror if we are using GCC.

  if test "x$GCC" = "xyes"; then

 -  XCFLAGS="$XCFLAGS -Wall -Werror"

 +  XCFLAGS="$XCFLAGS -Wall"

  fi

  # Find other programs we need.