Add TCMALLOC_NO_NEW_DELETE_OVERRIDES/TCMALLOC_NO_C_ALLOC_OVERRIDES

Since sometimes program already overwrites new/delete.

tcmalloc/libc_override_gcc_and_weak.h

@@ -36,6 +36,7 @@
 #define TCMALLOC_ALIAS(tc_fn) \
   __attribute__((alias(#tc_fn), visibility("default")))
 
+#ifndef TCMALLOC_NO_NEW_DELETE_OVERRIDES
 void* operator new(size_t size) noexcept(false)
     TCMALLOC_ALIAS(TCMallocInternalNew);
 void operator delete(void* p) noexcept TCMALLOC_ALIAS(TCMallocInternalDelete);
@@ -81,7 +82,9 @@ void operator delete[](void* p, std::align_val_t alignment,
 void operator delete[](void* p, size_t size,
                        std::align_val_t alignemnt) noexcept
     TCMALLOC_ALIAS(TCMallocInternalDeleteArraySizedAligned);
+#endif // \TCMALLOC_NO_NEW_DELETE_OVERRIDES
 
+#ifndef TCMALLOC_NO_C_ALLOC_OVERRIDES
 extern "C" {
 void* malloc(size_t size) noexcept TCMALLOC_ALIAS(TCMallocInternalMalloc);
 void free(void* ptr) noexcept TCMALLOC_ALIAS(TCMallocInternalFree);
@@ -109,5 +112,6 @@ size_t malloc_size(void* p) noexcept TCMALLOC_ALIAS(TCMallocInternalMallocSize);
 size_t malloc_usable_size(void* p) noexcept
     TCMALLOC_ALIAS(TCMallocInternalMallocSize);
 }   // extern "C"
+#endif // \TCMALLOC_NO_C_ALLOC_OVERRIDES
 
 #endif  // TCMALLOC_LIBC_OVERRIDE_GCC_AND_WEAK_INL_H_

tcmalloc/tcmalloc.h

@@ -24,9 +24,12 @@
 
 #include <malloc.h>
 #include <stddef.h>
+#include <new>
 
 #include "absl/base/attributes.h"
+#ifndef TCMALLOC_NO_NEW_DELETE_OVERRIDES
 #include "tcmalloc/internal/declarations.h"
+#endif
 
 // __THROW is defined in glibc systems.  It means, counter-intuitively,
 // "This function will never throw an exception."  It's an optional