Doxygen: Integrate doxygen building

Integrate the necessary things to generate doxygen.

Signed-off-by: Andreas Fuchs <andreas.fuchs@sit.fraunhofer.de>
diff --git a/.gitignore b/.gitignore
index 85ca7c0..7c3a893 100644
--- a/.gitignore
+++ b/.gitignore
@@ -66,3 +66,10 @@
 # ignore all files in test/unit without a file extension
 test/unit/*
 test/unit/!*.*
+doc/Doxyfile
+doc/doxy/
+doc/html/
+doc/man/
+tpm2-tss-2.0.0-dev.tar.gz
+tpm2-tss-2.0.0-dev/
+