Fix build break for Clang builds.
Summary:
Complains about
```
In file included from crypto/lib/cpp/CryptoException.cpp:1:
In file included from crypto/lib/cpp/CryptoException.h:5:
In file included from ./folly/Conv.h:30:
./folly/Range.h:573:19: error: redefinition of default argument
Comp eq = Comp()) {
^ ~~~~~~
./folly/Range.h:55:26: note: previous definition is here
Comp eq = Comp());
^ ~~~~~~
```
Redefinition of default arguments is not allowed in C++.
Test Plan:
```
fbconfig --clang admarket/adpublisher && fbmake dbg
```
contbuild, etc.
Reviewed By: lucian@fb.com
FB internal diff:
D910800