cc: clean up cray compilers, fix issues with case-insensitive filesystems (#10323)

* Remove Cray CC compilers causing problems on case-insensitive filesystems
* cray -> cce
* Ensure that compiler-specific directory comes first in build-env
* Point to compiler-specific symlinks

lib/spack/env/cce/case-insensitive/CC

@@ -0,0 +1 @@
+../../cc

lib/spack/env/cray/CC

@@ -1 +0,0 @@
-../cc

lib/spack/env/craype/CC

@@ -1 +0,0 @@
-../cc

lib/spack/env/craype/cc

@@ -1 +0,0 @@
-../cc

lib/spack/env/craype/ftn

@@ -1 +0,0 @@
-../cc

lib/spack/spack/build_environment.py

@@ -342,7 +342,7 @@ def set_build_environment_variables(pkg, env, dirty):
         if os.path.isdir(ci):
             env_paths.append(ci)
 
-    for item in reversed(env_paths):
+    for item in env_paths:
         env.prepend_path('PATH', item)
     env.set_path(SPACK_ENV_PATH, env_paths)
 

lib/spack/spack/compilers/cce.py

@@ -26,10 +26,10 @@ class Cce(Compiler):
     PrgEnv = 'PrgEnv-cray'
     PrgEnv_compiler = 'cce'
 
-    link_paths = {'cc': 'cc',
-                  'cxx': 'c++',
-                  'f77': 'f77',
-                  'fc': 'fc'}
+    link_paths = {'cc': 'cce/cc',
+                  'cxx': 'cce/case-insensitive/CC',
+                  'f77': 'cce/ftn',
+                  'fc': 'cce/ftn'}
 
     @classmethod
     def default_version(cls, comp):