[sanitizer] Only set soft coredump limit.

[eugenis]

Summary

If user wants to raise it back, let them.

compiler-rt/trunk/lib/sanitizer_common/sanitizer_posix_libcdep.cc

 
 static rlim_t getlim(int res) {
   rlimit rlim;
   CHECK_EQ(0, getrlimit(res, &rlim));
   return rlim.rlim_cur;
 }
 
 static void setlim(int res, rlim_t lim) {
-  // The following magic is to prevent clang from replacing it with memset.
-  volatile struct rlimit rlim;
+  struct rlimit rlim;
+  if (getrlimit(res, const_cast<struct rlimit *>(&rlim))) {
+    Report("ERROR: %s getrlimit() failed %d\n", SanitizerToolName, errno);
+    Die();
+  }
   rlim.rlim_cur = lim;
-  rlim.rlim_max = lim;
   if (setrlimit(res, const_cast<struct rlimit *>(&rlim))) {
     Report("ERROR: %s setrlimit() failed %d\n", SanitizerToolName, errno);
     Die();
   }
 }
 
 void DisableCoreDumperIfNecessary() {
   if (common_flags()->disable_coredump) {

compiler-rt/trunk/test/sanitizer_common/TestCases/corelimit.cc

 // RUN: %clangxx -O0 %s -o %t && %run %t
 // UNSUPPORTED: lsan,ubsan
 
 #include <assert.h>
 #include <sys/time.h>
 #include <sys/resource.h>
 
 int main() {
   struct rlimit lim_core;
   getrlimit(RLIMIT_CORE, &lim_core);
   void *p;
   if (sizeof(p) == 8) {
-    assert(0 == lim_core.rlim_max);
+    assert(0 == lim_core.rlim_cur);
   }
   return 0;
 }