libsframe: correct binary search for SFrame FDE

libsframe: correct binary search for SFrame FDE

sframe_get_funcdesc_with_addr_internal erroneously returns the last FDE,
if its function start address is lower than the searched for address.

Simplify the binary search for a SFrame FDE for a given address.  Only
return an FDE, if the searched for address is within the bounds of the
FDE function start address and function size.

libsframe/
	* sframe.c (sframe_get_funcdesc_with_addr_internal): Correct
	binary search for SFrame FDE.

libsframe/testsuite/
	* libsframe.find/plt-findfre-1.c: Add test for out of range
	PLT6.

Signed-off-by: Jens Remus <jremus@linux.ibm.com>