[analyzer][CrossTU][NFC] Generalize to external definitions instead of external functions

Summary: This is just changing naming and documentation to be general about external definitions that can be imported for cross translation unit analysis. There is at least a plan to add VarDecls: D46421

Reviewers: NoQ, xazax.hun, martong, a.sidorin, george.karpenkov, serge-sans-paille

Reviewed By: xazax.hun, martong

Subscribers: mgorny, whisperity, baloghadamsoftware, szepet, rnkovacs, mikhail.ramalho, Szelethus, donat.nagy, dkrupp, cfe-commits

Differential Revision: https://reviews.llvm.org/D56441

llvm-svn: 350852
diff --git a/clang/tools/scan-build-py/libscanbuild/clang.py b/clang/tools/scan-build-py/libscanbuild/clang.py
index ab42206..0cbfdb6 100644
--- a/clang/tools/scan-build-py/libscanbuild/clang.py
+++ b/clang/tools/scan-build-py/libscanbuild/clang.py
@@ -156,12 +156,12 @@
     return checkers
 
 
-def is_ctu_capable(func_map_cmd):
-    """ Detects if the current (or given) clang and function mapping
+def is_ctu_capable(extdef_map_cmd):
+    """ Detects if the current (or given) clang and external definition mapping
     executables are CTU compatible. """
 
     try:
-        run_command([func_map_cmd, '-version'])
+        run_command([extdef_map_cmd, '-version'])
     except (OSError, subprocess.CalledProcessError):
         return False
     return True