[analyzer] Explain why we have system-header-simulator*.h files.

Suggested by Csaba. Text based on an e-mail of mine on cfe-dev.

llvm-svn: 174213
diff --git a/clang/test/Analysis/Inputs/system-header-simulator-cxx.h b/clang/test/Analysis/Inputs/system-header-simulator-cxx.h
index e762d0a..faca0b4 100644
--- a/clang/test/Analysis/Inputs/system-header-simulator-cxx.h
+++ b/clang/test/Analysis/Inputs/system-header-simulator-cxx.h
@@ -1,3 +1,8 @@
+// Like the compiler, the static analyzer treats some functions differently if
+// they come from a system header -- for example, it is assumed that system
+// functions do not arbitrarily free() their parameters, and that some bugs
+// found in system headers cannot be fixed by the user and should be
+// suppressed.
 #pragma clang system_header
 
 namespace std {
diff --git a/clang/test/Analysis/Inputs/system-header-simulator-for-simple-stream.h b/clang/test/Analysis/Inputs/system-header-simulator-for-simple-stream.h
index 99986f4..f08f3f6 100644
--- a/clang/test/Analysis/Inputs/system-header-simulator-for-simple-stream.h
+++ b/clang/test/Analysis/Inputs/system-header-simulator-for-simple-stream.h
@@ -1,4 +1,8 @@
-
+// Like the compiler, the static analyzer treats some functions differently if
+// they come from a system header -- for example, it is assumed that system
+// functions do not arbitrarily free() their parameters, and that some bugs
+// found in system headers cannot be fixed by the user and should be
+// suppressed.
 #pragma clang system_header
 
 typedef struct __sFILE {
diff --git a/clang/test/Analysis/Inputs/system-header-simulator-objc.h b/clang/test/Analysis/Inputs/system-header-simulator-objc.h
index a647b37..ecc99e1 100644
--- a/clang/test/Analysis/Inputs/system-header-simulator-objc.h
+++ b/clang/test/Analysis/Inputs/system-header-simulator-objc.h
@@ -1,3 +1,8 @@
+// Like the compiler, the static analyzer treats some functions differently if
+// they come from a system header -- for example, it is assumed that system
+// functions do not arbitrarily free() their parameters, and that some bugs
+// found in system headers cannot be fixed by the user and should be
+// suppressed.
 #pragma clang system_header
 
 typedef unsigned int UInt32;
diff --git a/clang/test/Analysis/Inputs/system-header-simulator.h b/clang/test/Analysis/Inputs/system-header-simulator.h
index e28b890..4c12131 100644
--- a/clang/test/Analysis/Inputs/system-header-simulator.h
+++ b/clang/test/Analysis/Inputs/system-header-simulator.h
@@ -1,3 +1,8 @@
+// Like the compiler, the static analyzer treats some functions differently if
+// they come from a system header -- for example, it is assumed that system
+// functions do not arbitrarily free() their parameters, and that some bugs
+// found in system headers cannot be fixed by the user and should be
+// suppressed.
 #pragma clang system_header
 
 typedef struct _FILE FILE;