fix a couple of buglets and set version number on DLLs to whatever the PHP major version is.

Search for pecl extensions under php-src/pecl as a convenience for
pecl developers.
Add automatic version info resource generation for SAPI and extension
modules, based on PHP version num

Search for pecl extensions under php-src/pecl as a convenience for
pecl developers.
Add automatic version info resource generation for SAPI and extension
modules, based on PHP version numbers and info found in the CREDITS file.
As a nice side effect, this lets us add a logo icon to .exe files.

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