Fix some (digital-mars) compiler warnings

In particular, conditional expressions which contain an
assignment statement, where the expression type is not
explicitly made to be boolean, elicits the following
message:
    warning 2: possible unintended assignment

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

src/delta-apply.c

@@ -47,7 +47,7 @@ int git__delta_apply(
 		return GIT_ERROR;
 
 	res_sz = hdr_sz(&delta, delta_end);
-	if (!(res_dp = git__malloc(res_sz + 1)))
+	if ((res_dp = git__malloc(res_sz + 1)) == NULL)
 		return GIT_ERROR;
 	res_dp[res_sz] = '\0';
 	out->data = res_dp;

src/fileops.c

@@ -232,7 +232,7 @@ int gitfo_dirent(
 	if (!dir)
 		return git_os_error();
 
-	while ((de = readdir(dir))) {
+	while ((de = readdir(dir)) != NULL) {
 		size_t de_len;
 		int result;
 

src/odb.c

@@ -558,7 +558,7 @@ static int pack_openidx_v1(git_pack *p)
 	size_t expsz;
 	int j;
 
-	if (!(im_fanout = git__malloc(sizeof(*im_fanout) * 256)))
+	if ((im_fanout = git__malloc(sizeof(*im_fanout) * 256)) == NULL)
 		return GIT_ERROR;
 
 	im_fanout[0] = decode32(&src_fanout[0]);
@@ -615,7 +615,7 @@ static int pack_openidx_v2(git_pack *p)
 	uint32_t *im_fanout;
 	int j;
 
-	if (!(im_fanout = git__malloc(sizeof(*im_fanout) * 256)))
+	if ((im_fanout = git__malloc(sizeof(*im_fanout) * 256)) == NULL)
 		return GIT_ERROR;
 
 	im_fanout[0] = decode32(&src_fanout[0]);
@@ -751,11 +751,11 @@ static int scan_one_pack(void *state, char *name)
 	if (gitfo_exists(name))
 		return 0;
 
-	if (!(r = git__malloc(sizeof(*r))))
+	if ((r = git__malloc(sizeof(*r))) == NULL)
 		return GIT_ERROR;
 
 	*d = '\0';               /* "pack-abc.pack" -_> "pack-abc" */
-	if (!(r->pack = alloc_pack(s + 1))) {
+	if ((r->pack = alloc_pack(s + 1)) == NULL) {
 		free(r);
 		return GIT_ERROR;
 	}
@@ -811,7 +811,7 @@ static git_packlist *packlist_get(git_odb *db)
 	git_packlist *pl;
 
 	gitlck_lock(&db->lock);
-	if ((pl = db->packlist))
+	if ((pl = db->packlist) != NULL)
 		pl->refcnt++;
 	else
 		pl = scan_packs(db);

src/util.c

@@ -67,7 +67,7 @@ int git__dirname(char *dir, size_t n, char *path)
 
 	assert(dir && n > 1);
 
-	if (!path || !*path || !(s = strrchr(path, '/'))) {
+	if (!path || !*path || (s = strrchr(path, '/')) == NULL) {
 		strcpy(dir, ".");
 		return 1;
 	}
@@ -99,7 +99,7 @@ int git__basename(char *base, size_t n, char *path)
 	}
 	len = strlen(path);
 
-	if (!(s = strrchr(path, '/'))) {
+	if ((s = strrchr(path, '/')) == NULL) {
 		if (len >= n)
 			return GIT_ERROR;
 		strcpy(base, path);