musl: ldso/dlsym: fix mips returning undef dlsym

musl: ldso/dlsym: fix mips returning undef dlsym

This happens only the second time a library is loaded by dlopen().
After lib1 is loaded, dlsym(lib1,"undef1") correctly resolves the undef
symbol from lib1 dependencies. After the second library is loaded,
dlsym(lib2,"undef1") was returning the address of "undef1" in lib2
instead of searching lib2 dependencies.

Backporting upstream fix which now uses the same logic for relocation
time and dlsym.

Fixes openwrt/packages#9297

Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>