Merged revision(s) 1075807, 1241583, 1241983-1241984, 1241987, 1242010, 1242050, 1242068 from perl/modperl/branches/threading:
reintroduce MP_dTHX macro
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modperl_interp_pool_select() when used to create or merge dir-configs
at runtime may pull the interpreter from the wrong pool if the request's
server is a vhost with a separate interpreter pool.

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improve MP_TRACE output a bit: include current perl context for
threaded perls

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rename assert() => ap_assert()
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similar to r1241583: make sure r->server is used to identify the interpreter
pool to pull from at runtime.

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comment added
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remove a bit of code complexity

modperl_module.c contains these 2 lines:

	interp = modperl_interp_pool_select(p, s);
	MP_PERL_CONTEXT_STORE_OVERRIDE(interp->perl);

The latter decodes as

	orig_perl = PERL_GET_CONTEXT;
	aTHX = interp->perl;
	PERL_SET_CONTEXT(aTHX);

Now, modperl_interp_pool_select() already calls PERL_SET_CONTEXT with the
newly allocated interpreter. So, we get

	PERL_SET_CONTEXT(interp->perl);
	orig_perl = PERL_GET_CONTEXT;
	aTHX = interp->perl;
	PERL_SET_CONTEXT(aTHX);

But this is the same as

	interp = modperl_interp_pool_select(p, s);
	aTHX = interp->perl;

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ap_assert => MP_ASSERT (depends on MP_DEBUG)
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git-svn-id: https://svn.apache.org/repos/asf/perl/modperl/branches/httpd24threading@1537772 13f79535-47bb-0310-9956-ffa450edef68