Enable creation of large response file on z/OS

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.

Reviewed By: abhina.sreeskantharajan

Differential Revision: https://reviews.llvm.org/D100197

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

@@ -1,8 +0,0 @@
-#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

@@ -13,7 +13,7 @@
 // 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;