MFH: r441265
WITH_CCACHE_BUILD: Don't leak ccache in as a runtime-dependency.
fmake and bmake's := feature does not evaluate a variable immediately
if it does not yet exist (bmake's manpage notes this). In this case
BUILD_DEPENDS is empty but later gets ccache added to it. So when
RUN_DEPENDS is finally evaluated it actually gets ccache in it.
This line was not useful anyhow since there were not BUILD_DEPENDS to add
in; LIB_DEPENDS is its own unique thing that works as a BUILD and RUN
dependency but not directly related to the other variables.
Sponsored by: Dell EMC Isilon
Approved by: portmgr (implicit)