Disable stripping on installation

Using the -s option of install does not work, as it uses the host
strip instead of the cross strip. So, get rid of it, and let Buildroot
handle the stripping.

[Vincent: tweak patch for version 1.2]

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>

diff -Nrua a/configure b/configure
--- a/configure	2015-10-02 21:29:04.000000000 +0100
+++ b/configure	2015-10-06 13:28:37.245349592 +0100
@@ -2780,7 +2780,7 @@
 
 
 # Checking for CFLAGS
-_install_strip="-s"
+_install_strip=
 if test -z "$CFLAGS" || test "$_profile" != "" || test "$_debug" != ""; then
   if test "$cc_vendor" = "intel" ; then
     CFLAGS="-O2 $_march $_mcpu $_pipe -fomit-frame-pointer"