Add jemalloc include dir during build
Test for jemalloc >= 3.0.0 before using
Add vim swapfiles to .gitignore
Add LINK_PAM option to force linking pam
Don't use DEEPBIND flag in dlopen
Turn off rpath usage

CMake uses rpath to allow programs linked against local libraries to be run,
unfortunately this causes `make install` to re-link the installed targets so
it can change the rpath. For `hhvm`, this means it never gets the systemlib
added.
Add systemlibs as dependencies to the target they are being embedded in