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Making signx[] an int in alg_quant() and removes unnecessary sign copying

No measurable speed change.

--- a/celt/vq.c

+++ b/celt/vq.c

@@ -163,7 +163,7 @@

 {

    VARDECL(celt_norm, y);

    VARDECL(int, iy);

-   VARDECL(opus_val16, signx);

+   VARDECL(int, signx);

    int i, j;

    int pulsesLeft;

    opus_val32 sum;

@@ -177,7 +177,7 @@

    ALLOC(y, N, celt_norm);

    ALLOC(iy, N, int);

-   ALLOC(signx, N, opus_val16);

+   ALLOC(signx, N, int);

    exp_rotation(X, N, 1, B, K, spread);

@@ -184,9 +184,8 @@

    /* Get rid of the sign */

    sum = 0;

    j=0; do {

-      /* OPT: Make sure the following two lines result in conditional moves

-         rather than branches. */

-      signx[j] = X[j]>0 ? 1 : -1;

+      signx[j] = X[j]<0;

+      /* OPT: Make sure the compiler doesn't use a branch on ABS16(). */

       X[j] = ABS16(X[j]);

       iy[j] = 0;

       y[j] = 0;

@@ -318,10 +317,10 @@

    /* Put the original sign back */

    j=0;

    do {

-      X[j] = MULT16_16(signx[j],X[j]);

-      /* OPT: Make sure your compiler uses a conditional move here rather than

-         a branch. */

-      iy[j] = signx[j] < 0 ? -iy[j] : iy[j];

+      /*iy[j] = signx[j] ? -iy[j] : iy[j];*/

+      /* OPT: The is more likely to be compiled without a branch than the code above

+         but has the same performance otherwise. */

+      iy[j] = (iy[j]^-signx[j]) + signx[j];

    } while (++j<N);

    encode_pulses(iy, N, K, enc);