Bump up PGMath Library to latest version. More transparent name of the branch,...

Bump up PGMath Library to latest version. More transparent name of the branch, version name equals branch name. (#13511)

var/spack/repos/builtin/packages/pgmath/package.py

@@ -11,10 +11,11 @@ class Pgmath(CMakePackage):
     """Flang's math library"""
 
     homepage = "https://github.com/flang-compiler/flang"
-    url      = "https://github.com/flang-compiler/flang/archive/flang_20180612.tar.gz"
+    url      = "https://github.com/flang-compiler/flang/archive/flang_20190329.tar.gz"
     git      = "https://github.com/flang-compiler/flang.git"
 
-    version('develop', branch='master')
+    version('master', branch='master')
+    version('20190329', sha256='b8c621da53829f8c53bad73125556fb1839c9056d713433b05741f7e445199f2')
     version('20180921', sha256='f33bd1f054e474f1e8a204bb6f78d42f8f6ecf7a894fdddc3999f7c272350784')
     version('20180612', sha256='6af858bea013548e091371a97726ac784edbd4ff876222575eaae48a3c2920ed')