htop: work-around old uClibc issue when static linking

htop wants to use backtrace() support from the C
library. Unfortunately, with old uClibc versions such as the one we
use for the ARC architecture, the backtrace() implementation is in
libubacktrace. In addition, this implementation needs dladdr()
support, which is in libdl, not available when static linking.

Since this problem no longer exists in more recent versions of uClibc,
we simply special case the ARC+static linking case, and make the
configure script believe that <execinfo.h> is not available.

Fixes:

  http://autobuild.buildroot.net/results/cdea351fad7a0f61ddec3e6a141da8da0523a902/



Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>