half_tan: Implement using tan

v2: Use full precision implementation

Reviewer: Jeroen Ketema <j.ketema@xs4all.nl>
Signed-off-by: Jan Vesely <jan.vesely@rutgers.edu>
llvm-svn: 322898
GitOrigin-RevId: 2813b4f8d9f9797f69cac72d685aabc366fcd523
4 files changed