Add explicit size_t conversions.

src/libsodium/crypto_pwhash/scryptsalsa208sha256/pwhash_scryptsalsa208sha256.c

@@ -34,7 +34,7 @@ pickparams(unsigned long long opslimit, const size_t memlimit,
             }
         }
     } else {
-        maxN = memlimit / (*r * 128);
+        maxN = memlimit / ((size_t) *r * 128);
         for (*N_log2 = 1; *N_log2 < 63; *N_log2 += 1) {
             if ((uint64_t) (1) << *N_log2 > maxN / 2) {
                 break;

src/libsodium/randombytes/sysrandom/randombytes_sysrandom.c

@@ -208,7 +208,7 @@ randombytes_sysrandom_buf(void * const buf, const size_t size)
         abort(); /* LCOV_EXCL_LINE */
     }
 #else
-    if (size > 0xffffffff) {
+    if (size > (size_t) 0xffffffff) {
         abort(); /* LCOV_EXCL_LINE */
     }
     if (! RtlGenRandom((PVOID) buf, (ULONG) size)) {

src/libsodium/sodium/utils.c

@@ -358,7 +358,7 @@ _sodium_malloc(const size_t size)
     size_t         total_size;
     size_t         unprotected_size;
 
-    if (size >= SIZE_MAX - page_size * 4U) {
+    if (size >= (size_t) SIZE_MAX - page_size * 4U) {
         errno = ENOMEM;
         return NULL;
     }
@@ -407,7 +407,7 @@ sodium_allocarray(size_t count, size_t size)
 {
     size_t total_size;
 
-    if (size >= SIZE_MAX / count) {
+    if (size >= (size_t) SIZE_MAX / count) {
         errno = ENOMEM;
         return NULL;
     }