new gcc thinks some arrays get overrun, they don't, change

slightly so it won't warn..

The [5] change is the biggest question, and not sure how to
fix it better than this..

strobe/x25519.c

@@ -117,7 +117,7 @@ swapout(uint8_t *out, limb_t *x) {
     memcpy(out,x,sizeof(fe));
 }
 
-static void mul(fe out, const fe a, const fe b, unsigned nb) {
+static void mul(fe out, const fe a, const limb_t b[], unsigned nb) {
     /* GCC at least produces pretty decent asm for this, so don't need to have dedicated asm. */
     limb_t accum[2*NLIMBS] = {0};
     unsigned i,j;
@@ -188,9 +188,9 @@ static limb_t canon(fe x) {
     return ((dlimb_t)res - 1) >> X25519_WBITS;
 }
 
-static const limb_t a24[1]={121665};
+static const limb_t a24[1] = { 121665 };
 
-static void ladder_part1(fe xs[5]) {
+static void ladder_part1(fe xs[]) {
     limb_t *x2 = xs[0], *z2=xs[1],*x3=xs[2],*z3=xs[3],*t1=xs[4];
     add(t1,x2,z2);  // t1 = A
     sub(z2,x2,z2);  // z2 = B
@@ -216,7 +216,7 @@ static void ladder_part2(fe xs[5], const fe x1) {
     mul1(x2,t1);    // x2 = AA*BB
 }
 
-static void x25519_core(fe xs[5], const uint8_t scalar[X25519_BYTES], const uint8_t *x1, int clamp) {
+static void x25519_core(fe xs[], const uint8_t scalar[X25519_BYTES], const uint8_t *x1, int clamp) {
     int i;
 #if X25519_MEMCPY_PARAMS
     fe x1i;
@@ -312,7 +312,7 @@ const uint8_t X25519_BASE_POINT[X25519_BYTES] = {9};
 
 #if X25519_SUPPORT_VERIFY
 static limb_t x25519_verify_core(
-    fe xs[5],
+    fe xs[],
     const limb_t *other1,
     const uint8_t other2[X25519_BYTES]
 ) {