tests: Do not exit on an expected failure code.

The comment in the code below the patched line
clearly suggests that it should go on in this case.
This condition occurs on Alpine Linux (musl-libc-based):
http://patchwork.alpinelinux.org/patch/2206/

tests/set-rpath-library.sh

@@ -26,7 +26,6 @@ exitCode=0
 
 if test "$exitCode" = 46; then
     echo "expected failure"
-    exit 1
 fi
 
 # So set an RUNPATH on libfoo as well.