ld.so: Support moving versioned symbols between sonames [BZ #24741]

This change should be fully backwards-compatible because the old
code aborted the load if a soname mismatch was encountered
(instead of searching further for a matching symbol).  This means
that no different symbols are found.

The soname check was explicitly disabled for the skip_map != NULL
case.  However, this only happens with dl(v)sym and RTLD_NEXT,
and those lookups do not come with a verneed entry that could be used
for the check.

The error check was already explicitly disabled for the skip_map !=
NULL case, that is, when dl(v)sym was called with RTLD_NEXT.  But
_dl_vsym always sets filename in the struct r_found_version argument
to NULL, so the check was not active anyway.  This means that
symbol lookup results for the skip_map != NULL case do not change,
either.

1 files changed, 3 insertions, 0 deletions

diff --git a/elf/tst-sonamemove-runmod1.map b/elf/tst-sonamemove-runmod1.map
new file mode 100644
index 0000000000..2ea81c6e6f
--- /dev/null
+++ b/elf/tst-sonamemove-runmod1.map
@@ -0,0 +1,3 @@
+SONAME_MOVE {
+  global: other_function;
+};