libdl: fix local symbol's address handling in dladdr

libdl: fix local symbol's address handling in dladdr

Fix dladdr to correctly handle local function's address so backtrace_symbols
print only the function address for these function, instead of showing the name
of nearest one.
Indeed the dladdr walk through the hash table to find the nearest symbol, that
doesn't contain local symbols.

Signed-off-by: Filippo Arcidiacono <filippo.arcidiacono@st.com>
Signed-off-by: Carmelo Amoroso <carmelo.amoroso@st.com>