Created a new port: devel/picojson
Wrong place in the Makefile. See 15. Order of Variables in Port Makefiles.
Move the options block below ALL_TARGET.
Looking at picojson's Makefile  it does not seem to build anything and this will cause
Updated Makefile as suggested by tobik;
Added NO_BUILD= yes
Added TEST_TARGET= check
Moved 'OPTIONS' variables down for correct ordering
Shortened a line that was > 80 chars