Add annotations for Coverity FPs

src/libsodium/crypto_sign/edwards25519sha512batch/ref/sc25519_edwards25519sha512batch.c

@@ -46,10 +46,14 @@ static void barrett_reduce(sc25519 *r, const crypto_uint32 x[64])
   q2[33] += carry;
 
   for(i=0;i<33;i++)r1[i] = x[i];
-  for(i=0;i<32;i++)
-    for(j=0;j<33;j++)
-      if(i+j < 33) r2[i+j] += m[i]*q3[j];
-
+  for(i=0;i<32;i++) {
+    for(j=0;j<33;j++) {
+      if(i+j < 33) {
+          /* coverity[overrun-local] */
+          r2[i+j] += m[i]*q3[j];
+      }
+    }
+  }
   for(i=0;i<32;i++)
   {
     carry = r2[i] >> 8;

src/libsodium/randombytes/salsa20/randombytes_salsa20_random.c

@@ -279,6 +279,7 @@ randombytes_salsa20_random_buf(void * const buf, const size_t size)
     randombytes_salsa20_random_stir_if_needed();
     COMPILER_ASSERT(sizeof stream.nonce == crypto_stream_salsa20_NONCEBYTES);
 #ifdef ULONG_LONG_MAX
+    /* coverity[result_independent_of_operands] */
     assert(size <= ULONG_LONG_MAX);
 #endif
     ret = crypto_stream_salsa20((unsigned char *) buf, (unsigned long long) size,

src/libsodium/randombytes/sysrandom/randombytes_sysrandom.c

@@ -202,6 +202,7 @@ randombytes_sysrandom_buf(void * const buf, const size_t size)
 {
     randombytes_sysrandom_stir_if_needed();
 #ifdef ULONG_LONG_MAX
+    /* coverity[result_independent_of_operands] */
     assert(size <= ULONG_LONG_MAX);
 #endif
 #ifndef _WIN32