Move a few stray header files into the crypto subdir.

sshblowf.h (as was) is 100% internal to that directory. And mpint_i.h
and ecc.h are specialist enough that it's reasonable to ask clients
outside the crypto directory to include them with a subdirectory path,
to hint that it's an unusual thing to be doing.

crypto/bcrypt.c

@@ -9,7 +9,7 @@
 #include <stddef.h>
 #include <string.h>
 #include "ssh.h"
-#include "sshblowf.h"
+#include "blowfish.h"
 
 BlowfishContext *bcrypt_setup(const unsigned char *key, int keybytes,
                               const unsigned char *salt, int saltbytes)

crypto/blowfish.c

@@ -7,7 +7,7 @@
 #include <assert.h>
 #include <stdio.h>
 #include "ssh.h"
-#include "sshblowf.h"
+#include "blowfish.h"
 
 struct BlowfishContext {
     uint32_t S0[256], S1[256], S2[256], S3[256], P[18];

mpunsafe.c

@@ -7,7 +7,7 @@
 #include "puttymem.h"
 
 #include "mpint.h"
-#include "mpint_i.h"
+#include "crypto/mpint_i.h"
 
 /*
  * This global symbol is also defined in ssh2kex-client.c, to ensure

testcrypt.c

@@ -34,7 +34,7 @@
 #include "sshkeygen.h"
 #include "misc.h"
 #include "mpint.h"
-#include "ecc.h"
+#include "crypto/ecc.h"
 
 static NORETURN PRINTF_LIKE(1, 2) void fatal_error(const char *p, ...)
 {

testsc.c

@@ -79,7 +79,7 @@
 #include "ssh.h"
 #include "misc.h"
 #include "mpint.h"
-#include "ecc.h"
+#include "crypto/ecc.h"
 
 static NORETURN PRINTF_LIKE(1, 2) void fatal_error(const char *p, ...)
 {