Add version check when building intel-tbb with clang (#13893)

* Add version check when building with clang

* Update for flake8 formatting

var/spack/repos/builtin/packages/intel-tbb/package.py

@@ -53,6 +53,16 @@ class IntelTbb(Package):
 
     provides('tbb')
 
+    # Clang builds incorrectly determine GCC version which in turn incorrectly
+    # causes a mismatch in C++ features resulting in a link error. This also
+    # means that clang builds require a gcc compiler to work correctly (this
+    # has always been the case).
+    #
+    #    See https://github.com/intel/tbb/pull/147 for details.
+    #
+    conflicts('%clang', when='@:2019.7',
+              msg='2019.7 or later required for clang')
+
     conflicts('%gcc@6.1:', when='@:4.4.3',
               msg='4.4.4 or later required for GCC >= 6.1.')