Syncing this up with CMake.
Source code uses the built-in `OPENSSL_IS_AWSLC` and
`OPENSSL_IS_BORINSSL` macros to detect BoringSSL and AWS-LC. No help is
necessary from the build tools.
The one use of `HAVE_BORINGSSL` in the source turned out to be no longer
necessary for warning-free BoringSSL + Schannel builds. Ref: #1610#2634
autotools detects this anyway for display purposes.
CMake detects this to decide whether to use the BoringSSL-specific
crypto lib with ngtcp2. It detects AWS-LC, but doesn't use the detection
result just yet (planned in #12066).
Ref: #11964
Reviewed-by: Daniel Stenberg
Reviewed-by: Jay Satiro
Closes#12065
58a95b6a49