[TSan] Adjust tests for SystemZ

XFAIL map32bit, define the maximum possible allocation size in
mmap_large.cpp.

Reviewed By: dvyukov

Differential Revision: https://reviews.llvm.org/D105629

compiler-rt/test/tsan/map32bit.cpp

@@ -11,6 +11,7 @@
 // XFAIL: mips
 // XFAIL: aarch64
 // XFAIL: powerpc64
+// XFAIL: s390x
 
 // MAP_32BIT doesn't exist on OS X and NetBSD.
 // UNSUPPORTED: darwin,netbsd

compiler-rt/test/tsan/mmap_large.cpp

@@ -21,6 +21,8 @@ int main() {
   const size_t kLog2Size = 32;
 #elif defined(__powerpc64__)
   const size_t kLog2Size = 39;
+#elif defined(__s390x__)
+  const size_t kLog2Size = 43;
 #endif
   const uintptr_t kLocation = 0x40ULL << kLog2Size;
   void *p = mmap(