Fix wrong numbers being passed as string lengths

(Imported from upstream's 0b142f022e2c5072295e00ebc11c5b707a726d74.)

Modified further because these ought to just be BIO_puts.

Change-Id: I8b70d70d0f626bb19b455adb4f0e08bacf453c1d
Reviewed-on: https://boringssl-review.googlesource.com/4002
Reviewed-by: Adam Langley <agl@google.com>