sframe: fix PR libsframe/33051

Fix PR libsframe/Bug 33051 - ASAN: heap-buffer-overflow
../../src/libsframe/sframe.c:1054 in
sframe_get_funcdesc_with_addr_internal

The previous commit 9d2a24349e2 (libsframe: correct binary search for
SFrame FDE) adapted the binary search logic in
sframe_get_funcdesc_with_addr_internal.  Adjusting the upper end of the
search index was missed.

The search must only be done for FDEs starting at index 0 and up until
num_fdes - 1.  Prior logic of searching (before commit 9d2a24349e2) was
a bit different.

libsframe/
	* sframe.c: Use the correct high index.