uclibc: build uclibc unstripped by default

uclibc: build uclibc unstripped by default

uClibc can be built stripped (implemented as link-time option in uClibc).
This could be useful for those who build root fs manually.

In Buildroot there is a global strip stage wich strips most of shared libs
in "target" folder (wexcept kernel modules known to not work properly being
stripped and libpthread required to be non-stripped for correct debugging with
gdb of multi-threaded apps).

So there're few problems with current implementation:
 1. uClibc is being stripped 2 times (first on its build stage, second on
    global Buildroot strip stage)
 2. uClibc libs in "staging" folder are also always stripped except if
    "no strip" (BR2_STRIP_none) is explicitly is selected in Buildroot config.
    That makes it possible to remote debug uClibc libs on target only if target
    rootfs was not stripped (which might not be possible due to huge libs
    like Qt)

This patch disables embedded strip in uClibc (still users may modify uClibc
config and explicitly set "DOSTRIP=yes" if really needed).

Interesting that DOSTRIP was not only selected in uClibc config but also was
force set with Buildroot on uClibc configuration step with UCLIBC_STRIP_CONFIG.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Cc: Peter Korsgaard <peter@korsgaard.com>
Cc: Gustavo Zacarias <gustavo@zacarias.com.ar>
Cc: Thomas De Schampheleire <patrickdepinguin@gmail.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Waldemar Brodkorb <wbx@openadk.org>
Reviewed-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>