Check for nullptr return from malloc, calloc, and realloc. (#1023)

These are used in ntcore and cscore.  Add inline null-checking versions
to wpi/memory.h and use them throughout.

ntcore/src/main/native/cpp/WireDecoder.cpp

@@ -15,6 +15,7 @@
 
 #include <wpi/MathExtras.h>
 #include <wpi/leb128.h>
+#include <wpi/memory.h>
 
 using namespace nt;
 
@@ -52,7 +53,7 @@ WireDecoder::WireDecoder(wpi::raw_istream& is, unsigned int proto_rev,
   // Start with a 1K temporary buffer.  Use malloc instead of new so we can
   // realloc.
   m_allocated = 1024;
-  m_buf = static_cast<char*>(std::malloc(m_allocated));
+  m_buf = static_cast<char*>(wpi::CheckedMalloc(m_allocated));
   m_proto_rev = proto_rev;
   m_error = nullptr;
 }
@@ -71,7 +72,7 @@ void WireDecoder::Realloc(size_t len) {
   if (m_allocated >= len) return;
   size_t newlen = m_allocated * 2;
   while (newlen < len) newlen *= 2;
-  m_buf = static_cast<char*>(std::realloc(m_buf, newlen));
+  m_buf = static_cast<char*>(wpi::CheckedRealloc(m_buf, newlen));
   m_allocated = newlen;
 }