cleanup: reduce variable scopes in common.c

Contributes to #9.

src/libespeak-ng/common.c

 
 	int c1;
 	int n_bytes;
-	int ix;
 	static const unsigned char mask[4] = { 0xff, 0x1f, 0x0f, 0x07 };
 
 	// find the start of the next/previous character
 			n_bytes = 3;
 
 		c1 &= mask[n_bytes];
+		int ix;
 		for (ix = 0; ix < n_bytes; ix++)
 		{
 			if (!*buf)
 {
 	// Read 4 bytes (least significant first) into a word
 	int ix;
-	unsigned char c;
 	int acc = 0;
 
 	for (ix = 0; ix < 4; ix++) {
+		unsigned char c;
 		c = fgetc(f) & 0xff;
 		acc += (c << (ix*8));
 	}