This request does 2 things:
1. The doxygen/doxywizard C++ code in doxygen-1.8.20 triggers GCC bug 85180, leading to exorbitant compile times. This bug was fixed for GCC-8, but not backported to GCC-7 (also not included in the SUSE gcc7 package).
Workaround this bug by using the gcc9 package on SLE15 based distributions.
2. Adjust the libclang support to the changes in doxygen-1.8.20. This also disables libclang support for SLES15GA, because clang on SLES15GA is not compatible.
OBS-URL: https://build.opensuse.org/request/show/841435
OBS-URL: https://build.opensuse.org/package/show/devel:tools/doxygen?expand=0&rev=156
