Fix --disable-mining build regression. closes #4634

Signed-off-by: Daira Hopwood <daira@jacaranda.org>

src/crypto/equihash.h

@@ -5,6 +5,13 @@
 
 #ifndef BITCOIN_EQUIHASH_H
 #define BITCOIN_EQUIHASH_H
+
+
+inline constexpr size_t equihash_solution_size(unsigned int N, unsigned int K) {
+    return (1 << K)*(N/(K+1)+1)/8;
+}
+
+
 #ifdef ENABLE_MINING
 
 #include "crypto/sha256.h"
@@ -157,10 +164,6 @@ class EhSolverCancelledException : public std::exception
 
 inline constexpr const size_t max(const size_t A, const size_t B) { return A > B ? A : B; }
 
-inline constexpr size_t equihash_solution_size(unsigned int N, unsigned int K) {
-    return (1 << K)*(N/(K+1)+1)/8;
-}
-
 template<unsigned int N, unsigned int K>
 class Equihash
 {