libclaw-1.7.4-bp156.4.7

- Refresh no-boost-math.patch, limits header is missing in public
  header file, results in build errors with gcc11 of packages using it
- Refresh fix-cmake.patch, use upstream patch
- Refresh libclaw-doxy-w-date-time.patch

- Add no-boost-math.patch, as Boost.Math now (boost 1.76) requires
  c++11, but source code does not work with c++11, so replacing
  Boost.Math with standard functions.

- Added libclaw-1.7.4-gcc7.patch from Fedora.

- Use knwon good source URL

- Update descriptions and RPM groups.

- Added " -std=c++98" to CXXFLAGS to prevent build issue via gcc6.
- Removed unneeded baselibs.conf.

- Spec cleanup, now using cmake macros, fixed BuildRequires
  and created -doc subpackage.

- Initial build.