dev-libs/boost: remove unused file

Signed-off-by: Michael Mair-Keimberger <mm1ke@gentoo.org>

dev-libs/boost/files/unit-test-main.cpp

@@ -1,19 +0,0 @@
-/*
-  A synthetic main() to bootstrap an old-style test suite.
-  This seems to be necessary for older tests suites when enforcing
-  building against boost as shared library.
-  Further details can be found at:
-  https://www.boost.org/doc/libs/1_88_0/libs/test/doc/html/boost_test/adv_scenarios/obsolete_init_func.html
-*/
-
-bool init_master_suite(void)
-{
-  test_suite* master = &::boost::unit_test::framework::master_test_suite();
-  master->add(init_unit_test_suite(0, nullptr));
-  return true;
-}
-
-int main(int argc, char* argv[])
-{
-  return ::boost::unit_test::unit_test_main(init_master_suite, argc, argv);
-}