Make VPATH (srcdir != builddir) doc-api builds work (a different approach to r16451, and to r16462).
Make VPATH (srcdir != builddir) doc-api builds work (a different
approach to r16451, and to r16462).

* Makefile.in (doc-api): Preprocess doxygen.conf such that the path to the
    output directory is absolute, and cd to the source directory to run
    doxygen (the only way to get the proper relative paths embedded in the
    generated documentation).

Review by: dlr


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@856542 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion