[esan] Fix ESan test failure on Debian Sid bot

[zhaoqin]

Summary

Increase early allocation buffer size.

[bruening]

Ideally this would be shared with the other sanitizers. We're also not sure why the other sanitizers aren't failing on sid. But this should fix it short-term.

lib/esan/esan_interceptors.cpp

 #else
 #define ESAN_MAYBE_INTERCEPT_PTHREAD_SIGMASK
 #endif
 
 //===----------------------------------------------------------------------===//
 // Malloc interceptors
 //===----------------------------------------------------------------------===//
 
-static const uptr early_alloc_buf_size = 1024;
+static const uptr early_alloc_buf_size = 4096;
 static uptr allocated_bytes;
 static char early_alloc_buf[early_alloc_buf_size];
 
 static bool isInEarlyAllocBuf(const void *ptr) {
   return ((uptr)ptr >= (uptr)early_alloc_buf &&
           ((uptr)ptr - (uptr)early_alloc_buf) < sizeof(early_alloc_buf));
 }