Eliminate xdiff compiler warnings

This cleans up the various GCC compiler warnings with the
xdiff code that was copied in.

src/xdiff/xdiff.h

@@ -94,7 +94,7 @@ typedef struct s_xdemitconf {
 	unsigned long flags;
 	find_func_t find_func;
 	void *find_func_priv;
-	void (*emit_func)();
+	void (*emit_func)(void);
 } xdemitconf_t;
 
 typedef struct s_bdiffparam {

src/xdiff/xemit.c

@@ -71,6 +71,8 @@ xdchange_t *xdl_get_hunk(xdchange_t *xscr, xdemitconf_t const *xecfg) {
 
 static long def_ff(const char *rec, long len, char *buf, long sz, void *priv)
 {
+	(void)priv;
+
 	if (len > 0 &&
 			(isalpha((unsigned char)*rec) || /* identifier? */
 			 *rec == '_' ||	/* also identifier? */
@@ -91,6 +93,9 @@ static int xdl_emit_common(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
 	const char *rchg = xdf->rchg;
 	long ix;
 
+	(void)xscr;
+	(void)xecfg;
+
 	for (ix = 0; ix < xdf->nrec; ix++) {
 		if (rchg[ix])
 			continue;

src/xdiff/xhistogram.c

@@ -107,9 +107,10 @@ static int cmp_recs(xpparam_t const *xpp,
 #define TABLE_HASH(index, side, line) \
 	XDL_HASHLONG((REC(index->env, side, line))->ha, index->table_bits)
 
-static int scanA(struct histindex *index, int line1, int count1)
+static int scanA(struct histindex *index, unsigned int line1, unsigned int count1)
 {
-	unsigned int ptr, tbl_idx;
+	unsigned int ptr;
+	unsigned int tbl_idx;
 	unsigned int chain_len;
 	struct record **rec_chain, *rec;
 
@@ -160,8 +161,10 @@ continue_scan:
 	return 0;
 }
 
-static int try_lcs(struct histindex *index, struct region *lcs, int b_ptr,
-	int line1, int count1, int line2, int count2)
+static int try_lcs(
+	struct histindex *index, struct region *lcs, unsigned int b_ptr,
+	unsigned int line1, unsigned int count1,
+	unsigned int line2, unsigned int count2)
 {
 	unsigned int b_next = b_ptr + 1;
 	struct record *rec = index->records[TABLE_HASH(index, 2, b_ptr)];
@@ -233,9 +236,12 @@ static int try_lcs(struct histindex *index, struct region *lcs, int b_ptr,
 	return b_next;
 }
 
-static int find_lcs(struct histindex *index, struct region *lcs,
-	int line1, int count1, int line2, int count2) {
-	int b_ptr;
+static int find_lcs(
+	struct histindex *index, struct region *lcs,
+	unsigned int line1, unsigned int count1,
+	unsigned int line2, unsigned int count2)
+{
+	unsigned int b_ptr;
 
 	if (scanA(index, line1, count1))
 		return -1;
@@ -258,12 +264,14 @@ static int fall_back_to_classic_diff(struct histindex *index,
 				  line1, count1, line2, count2);
 }
 
-static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
-	int line1, int count1, int line2, int count2)
+static int histogram_diff(
+	xpparam_t const *xpp, xdfenv_t *env,
+	unsigned int line1, unsigned int count1,
+	unsigned int line2, unsigned int count2)
 {
 	struct histindex index;
 	struct region lcs;
-	int sz;
+	unsigned int sz;
 	int result = -1;
 
 	if (count1 <= 0 && count2 <= 0)

src/xdiff/xutils.c

@@ -372,8 +372,8 @@ int xdl_emit_hunk_hdr(long s1, long c1, long s2, long c2,
 	nb += 3;
 	if (func && funclen) {
 		buf[nb++] = ' ';
-		if (funclen > sizeof(buf) - nb - 1)
-			funclen = sizeof(buf) - nb - 1;
+		if (funclen > (long)sizeof(buf) - nb - 1)
+			funclen = (long)sizeof(buf) - nb - 1;
 		memcpy(buf + nb, func, funclen);
 		nb += funclen;
 	}