Enable creation of large response file on z/OS

[SeanP]

Summary

Most text processing commands (eg. grep, awk) have a maximum line length limit on z/OS. The current method of using cc -E & grep fails on z/OS because of this limit. I'm changing the command to create the long line in the response file to use python. This avoids the possibility of any tools blocking the generation of the large response file. This also eliminates the need for the extra file.

[abhina.sreeskantharajan]

LGTM

clang/test/Driver/Inputs/gen-response.c

-#define M -DTEST
-#define M1 M M M M M M M M M M
-#define M2 M1 M1 M1 M1 M1 M1 M1 M1 M1 M1
-#define M3 M2 M2 M2 M2 M2 M2 M2 M2 M2 M2
-#define M4 M3 M3 M3 M3 M3 M3 M3 M3 M3 M3
-#define M5 M4 M4 M4 M4 M4 M4 M4 M4 M4 M4
-#define TEXT M5 M5 M5
-TEXT

clang/test/Driver/response-file.c

 // Check that clang is able to process short response files
 // Since this is a short response file, clang must not use a response file
 // to pass its parameters to other tools. This is only necessary for a large
 // number of parameters.
 // RUN: echo "-DTEST" > %t.0.txt
 // RUN: %clang -E @%t.0.txt %s -v 2>&1 | FileCheck %s -check-prefix=SHORT
 // SHORT-NOT: Arguments passed via response file
 // SHORT: extern int it_works;
 
 // Check that clang is able to process long response files, routing a long
 // sequence of arguments to other tools by using response files as well.
 // We generate a 2MB response file to attempt to surpass any system limit.
 // But there's no guarantee that we actually will (the system limit could be
 // *huge*), so just check that invoking cc1 succeeds under these conditions.
 //
-// RUN: %clang -E %S/Inputs/gen-response.c | grep DTEST > %t.1.txt
+// RUN: %python  -c 'print(*("-DTEST" for x in range(300000)))' >%t.1.txt
 // RUN: %clang -E @%t.1.txt %s -v 2>&1 | FileCheck %s -check-prefix=LONG
 // LONG: extern int it_works;
 
 #ifdef TEST
 extern int it_works;
 #endif