make coverage-html on OS X

I've been trying to get $SUBJECT working, but all my lcov.info files are 
empty. I'm also getting warnings about no .da files.

I've slowly stripped away my normal build environment; I'm now using 
baseline gcc (no ccache) with the following ./configure... anyone have 
any ideas how to debug/fix this?

./configure --with-includes=/opt/local/include 
--with-libraries=/opt/local/lib --with-libxml --with-tcl --with-perl 
--with-python --enable-depend -C --enable-dtrace --enable-tap-tests 
--enable-coverage --enable-profiling --enable-cassert --enable-debug 
--prefix='/Users/decibel/pgsql/HEAD/i' --with-pgport=$PGC_PORT

gcov --version
Apple LLVM version 8.0.0 (clang-800.0.38)  Optimized build.  Default target: x86_64-apple-darwin15.6.0  Host CPU:
haswell

lcov --version
lcov: LCOV version 1.12

-- 
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
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