Rip out non-endomorphism code

src/ecmult.h

@@ -15,9 +15,7 @@
 typedef struct {
     /* For accelerating the computation of a*P + b*G: */
     secp256k1_ge_storage (*pre_g)[];    /* odd multiples of the generator */
-#ifdef USE_ENDOMORPHISM
     secp256k1_ge_storage (*pre_g_128)[]; /* odd multiples of 2^128*generator */
-#endif
 } secp256k1_ecmult_context;
 
 static const size_t SECP256K1_ECMULT_CONTEXT_PREALLOCATED_SIZE;