core/crypto: Expose the block sizes for every hash algorithm

While I just went and made this private, this information is required
for keying HMAC.

core/crypto/legacy/sha1/sha1.odin

@@ -23,9 +23,12 @@ import "core:encoding/endian"
 import "core:math/bits"
 import "core:mem"
 
-// DIGEST_SIZE is the SHA1 digest size.
+// DIGEST_SIZE is the SHA1 digest size in bytes.
 DIGEST_SIZE :: 20
 
+// BLOCK_SIZE is the SHA1 block size in bytes.
+BLOCK_SIZE :: 64
+
 // Context is a SHA1 instance.
 Context :: struct {
 	data:    [BLOCK_SIZE]byte,
@@ -138,9 +141,6 @@ reset :: proc(ctx: ^$T) {
     SHA1 implementation
 */
 
-@(private)
-BLOCK_SIZE :: 64
-
 @(private)
 transform :: proc "contextless" (ctx: ^Context, data: []byte) {
 	a, b, c, d, e, i, t: u32