Update: Add hopefully more secure compiler flags by default.

Update: Add hopefully more secure compiler flags by default.

Use the "-Wl" for specifying the linker flags.
- Make sure "now", "relro", and "nodlopen" are set.

Add FORTIFY_SOURCE set to 3.

Add stack-clash-protection and strict-flex-arrays set to 3.

This project is designed around NULL checks.
- Make sure the no-delete-null-pointer-checks flag is set to prevent the compiler from removing these security/integrity checks.

Use stack-protector-strong rather than stack-protector for test flags.
- Future versions may enable stack-protector-strong by default for regular compiling.