message: Fix distribution tarball generation
  Do not include pregenerated package config file, but include doctest
  header (whoops).
diff: ACLOCAL_AMFLAGS = --install -I builds/autoconf/m4
  -EXTRA_DIST = AUTHORS.md README.md builds generator
  +EXTRA_DIST = AUTHORS.md README.md generator \
  + builds/cmake builds/vs2015 builds/Doxyfile
  pkgconfigdir = ${libdir}/pkgconfig
  pkgconfig_DATA = builds/liblcf.pc
  @@ -195,6 +196,7 @@ pkginclude_HEADERS = \
  check_PROGRAMS = test_runner
  test_runner_SOURCES = \
  + tests/doctest.h \
  tests/time_stamp.cpp \
  tests/test_main.cpp
  test_runner_CPPFLAGS = \
  