[yocto] CMake in populate_sdk

[Benjamin Fleming]

How do I add packages to the populate_sdk option? 
I have an image (myimage) that depends on some custom packages which inherit the cmake bbclass. My expectation is that the populate_sdk task would notice that cmake is required for building and, as a result add cmake to the SDK. That is not the case. Also, for some reason, make is not included, either:

$ source /opt/poky/1.6.2/environment-setup-cortexa9hf-vfp-neon-poky-linux-gnueabi
$ which automake
/opt/poky/1.6.2/sysroots/x86_64-pokysdk-linux/usr/bin/automake
$ which make
usr/bin/make

What should I be adding to cause the inclusion of CMake in the SDK output? 

-Ben Fleming