Fixed documentation for hypothesis tests

Jira: MADLIB-624

Commit 884ff80 introduced a regression in that the three ordered-aggregate tests
{ks|mw|wsr}_test did no longer show up in the documentation. This has been
fixed. Also, all SQL macros that are otherwise defined in "SQLCommon.m4" are now
also define when running doxygen. This should increase the compatibility in the
future.

Biggest change: I moved the CMake macro 'define_m4_macros' from
PostgreSQLUtils.cmake to Utils.cmake.
6 files changed