libpng 1.6.16

Closes #35217.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
libpng: update 1.6.16 bottle.
test-bot: test bottled dependents.

Test everything that `brew uses` a formula, has a bottle and a test.

This should allow some quick gains in terms of spotting formulae that may need
revisioned to avoid problems with shifting dependencies. As the test-bot lives
in a data centre with (very) fast internet the fetch and extraction time
shouldn't slow things down much.

Closes #35092.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
libjson-rpc-cpp 0.4.1

Closes #33453.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
libjson-rpc-cpp: add 0.4.1 bottle.
wellington formula

* brew compiles and installs a static libsass
* pkg-config for reading the correct path
* updated for 3.1 instructions
* update for libsass 3.1beta2
audit warnings
pipe input into wt
enable cxx11 in the stage and install def
specify g++ external linker for ML
print build commands
wellington: add 0.5.0 bottle.