Beyond generally eliminating unnecessary includes, eliminate as many
includes of headers that declare/define particularly error-prone
functionality like strlen, malloc, and free. crypto/err/internal.h was
added to remove the dependency on openssl/thread.h from the public
openssl/err.h header. The include of <stdlib.h> in openssl/mem.h was
retained since it defines OPENSSL_malloc and friends as macros around
the stdlib.h functions. The public x509.h, x509v3.h, and ssl.h headers
were not changed in order to minimize breakage of source compatibility
with external code.

Change-Id: I0d264b73ad0a720587774430b2ab8f8275960329
Reviewed-on: https://boringssl-review.googlesource.com/4220
Reviewed-by: Adam Langley <agl@google.com>

At least the linker can discard this function in the cases where nobody
is calling it.

Change-Id: I30050e918e6bc1dd9c97cc70f3a56408701abebc
Reviewed-on: https://boringssl-review.googlesource.com/3724
Reviewed-by: Adam Langley <agl@google.com>

Because NTLM authentication is still a thing.

Change-Id: I3308a8431c82f0b614e09ce3e5efac1526881f1e
Reviewed-on: https://boringssl-review.googlesource.com/3723
Reviewed-by: Adam Langley <agl@google.com>

Caught by clang scan-build.

Change-Id: I4f10c879dc137d4a14a7a395764d28e5caa033ff
Reviewed-on: https://boringssl-review.googlesource.com/1342
Reviewed-by: Adam Langley <agl@google.com>

Initial fork from f2d678e6e8 (1.0.2 beta).

(This change contains substantial changes from the original and
effectively starts a new history.)