Speed up PDF generation and add timing debug output

... to the Doxygen generation log file `documentation/pdfall.log`.

The additions to the log file are intended to find out which parts
take how much time.

Note: use `grep "make_pdf" documentation/pdfall.log` to see the
  log output with timestamps.

- documentation/Doxyfile.in: exclude undocumented source files in
  src/xutf8/* which reduces parsing by a small amount of time,
  estimated about 5 percent of build time. YMMV.

1 files changed, 2 insertions, 1 deletions

diff --git a/documentation/Doxyfile.in b/documentation/Doxyfile.in
index e923d8c96..f9cfd528b 100644
--- a/documentation/Doxyfile.in
+++ b/documentation/Doxyfile.in
@@ -857,7 +857,8 @@ RECURSIVE              = YES
 # Note that relative paths are relative to the directory from which doxygen is
 # run.
 
-EXCLUDE                = @FLTK_SOURCE_DIR@/src/drivers/
+EXCLUDE                = @FLTK_SOURCE_DIR@/src/drivers/ \
+                         @FLTK_SOURCE_DIR@/src/xutf8/
 
 # The EXCLUDE_SYMLINKS tag can be used to select whether or not files or
 # directories that are symbolic links (a Unix file system feature) are excluded