Description:
------------
Looks as if the current lcov/gcov implementation works by:

* collecting all 'interesting' files and copying/linking them
  over to a new directory lcov_data

* then removing files for which actually no coverage information
  should be generated, like bundled library sources

* finally running lcov and genhtml over the lcov_data copies

As far as i can tell the removal of bundled library stuff is the
only real reason for the copy/symlink step, or am i missing
something else there?

Assuming that this is really the only reason i'd like to propose
to use 'lcov --remove' for filtering out the bundled library stuff
instead and to run lcov and genhtml in place instead of the new
lcov_data subdir, so skipping the need for this extra directory
and the process needed to populate it.

Advantages:

* less complex (Makefile.gcov line count shrinks from 64 to 30)

* no duplication of information

* shows coverage info for a few file that the current implementation
  misses for some reason unknown to me yet, like

  * main/internal_functions.c
  * main/internal_functions_cli.c
  * ext/standard/url_scanner_ex.re
  * ext/standard/var_unserializer.re
  * Zend/zend_language_scanner.l
  * Zend/zend_ini_scanner.l

Disadvantages:

 * 'lcov --remove' is rather slow, as far as i can tell the copy&remove
   approach is a tad quicker ... the difference is not relevant when
   compared with the total time needed for a lcov analysis run though

 * genhtml still generates HTML files for files filtered out by
   'lcov --remove', so taking a bit longer to run, the files do not
   show up in any of the result overview pages though

So all in all i think the advantages justify a change while the
disadvantages are not blocking it.

The only thing that actually changes would be the 'php_lcov.info'
target in 'Makgefile.gcov', the simplified version would look
like this:

php_lcov.info: lcov-test
    @echo "Generating $@"
    @$(LTP) --directory . --capture --base-directory . --output-file $@
    @echo "Stripping bundled libraries from $@"
    @for dir in ext/bcmath/libbcmath ext/fileinfo/libmagic ext/gd/libgd ext/mbstring/libmbfl ext/mbstring/oniguruma ext/pcre/pcrelib ext/pdo_sqlite/libsqlite ext/sqlite/libsqlite ext/sqlite3/libsqlite ext/xmlrpc/libxmlrpc ext/zip/lib; do \
        echo "... removing $$dir"; \
        $(LTP) --remove $@ $$dir/\* --output-file $@ ; \
    done
    @echo

Ideas, comments, any reasons *not* to commit this? 

Test script:
---------------
see Makefile.gcov implementation

Expected result:
----------------
LCOV report generated by patched PHP 5.3 "make lcov"
see http://php-baustelle.de/lcov_newhtml

Actual result:
--------------
LCOV report generated by unpatched PHP 5.3 "make lcov"
see http://php-baustelle.de/lcov_old65html