More portable gdb

[springmeyer]

gdb currently dynamically links libncurses, libexpat, and libtinfo which are not going to always be available. We should be statically linking them. Also refs #309.

# ldd ./mason_packages/linux-x86_64/gdb/7.12/bin/gdb
	linux-vdso.so.1 =>  (0x00007ffe793d8000)
	libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f6e23305000)
	libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f6e23101000)
	libncurses.so.5 => /lib/x86_64-linux-gnu/libncurses.so.5 (0x00007f6e22edd000)
	libtinfo.so.5 => /lib/x86_64-linux-gnu/libtinfo.so.5 (0x00007f6e22cb4000)
	libexpat.so.1 => /lib/x86_64-linux-gnu/libexpat.so.1 (0x00007f6e22a8a000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f6e22783000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f6e223be000)
	/lib64/ld-linux-x86-64.so.2 (0x0000563a39d45000)