Fixes the following security vulnerability:
- CVE-2019-19126: ld.so failed to ignore the LD_PREFER_MAP_32BIT_EXEC
environment variable during program execution after a security
transition, allowing local attackers to restrict the possible mapping
addresses for loaded libraries and thus bypass ASLR for a setuid
program. Reported by Marcin Kościelnicki.
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
b341c7497f