Resolve warnings in VC-WIN32 build, which allows to add /WX.

It's argued that /WX allows to keep better focus on new code, which
motivates its comeback...

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4721)

apps/apps.c

diff --git a/apps/apps.c b/apps/apps.c
index e25739e..fd81567 100644
--- a/apps/apps.c
+++ b/apps/apps.c
@@ -1926,7 +1926,7 @@
                 OPENSSL_free(out);
                 return NULL;
             }
-            out[start] = i - start;
+            out[start] = (unsigned char)(i - start);
             start = i + 1;
         } else {
             out[i + 1] = in[i];

apps/s_client.c

diff --git a/apps/s_client.c b/apps/s_client.c
index 58ed1a5..7c0639f 100644
--- a/apps/s_client.c
+++ b/apps/s_client.c
@@ -417,10 +417,11 @@
     unsigned char ext_buf[4 + 65536];
 
     /* Reconstruct the type/len fields prior to extension data */
-    ext_buf[0] = ext_type >> 8;
-    ext_buf[1] = ext_type & 0xFF;
-    ext_buf[2] = inlen >> 8;
-    ext_buf[3] = inlen & 0xFF;
+    inlen &= 0xffff; /* for formal memcmpy correctness */
+    ext_buf[0] = (unsigned char)(ext_type >> 8);
+    ext_buf[1] = (unsigned char)(ext_type);
+    ext_buf[2] = (unsigned char)(inlen >> 8);
+    ext_buf[3] = (unsigned char)(inlen);
     memcpy(ext_buf + 4, in, inlen);
 
     BIO_snprintf(pem_name, sizeof(pem_name), "SERVERINFO FOR EXTENSION %d",

apps/speed.c

diff --git a/apps/speed.c b/apps/speed.c
index 5f293ec..063bc1c 100644
--- a/apps/speed.c
+++ b/apps/speed.c
@@ -3198,8 +3198,8 @@
 
                 RAND_bytes(out, 16);
                 len += 16;
-                aad[11] = len >> 8;
-                aad[12] = len;
+                aad[11] = (unsigned char)(len >> 8);
+                aad[12] = (unsigned char)(len);
                 pad = EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_TLS1_AAD,
                                           EVP_AEAD_TLS1_AAD_LEN, aad);
                 EVP_Cipher(ctx, out, inp, len + pad);