mtmd: use sha256 for input hashing (#27274)

* mtmd: use sha256 for input hashing

* void conflict with boringssl

vendor/hash/sha1/sha1.c

@@ -25,6 +25,8 @@ A million repetitions of "a"
 
 #include "sha1.h"
 
+namespace vendor_hash {
+
 
 #define rol(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))
 
@@ -293,3 +295,5 @@ void SHA1(
     SHA1Final((unsigned char *)hash_out, &ctx);
 }
 
+} // namespace vendor_hash
+