PATCH: use SEEK_ macros in fseek() calls

[Oliver Kiddle <opk@xxxxxxx>]

When looking at the fseek in history contributions, I noticed that in
calls to fseek(), we have 0, 1 and 2 hard-coded for the whence parameter
in many but not all cases. Perhaps the SEEK_ macros couldn't be relied
upon in the distant past but we also do use them in some cases. I think
they make the code slightly more readable so this patch adds them in.

Oliver

diff --git a/Src/hist.c b/Src/hist.c
index 2e5ac97d9..42cae030c 100644
--- a/Src/hist.c
+++ b/Src/hist.c
@@ -2664,7 +2664,7 @@ readhistfile(char *fn, int err, int readflags)
 	pushheap();
 	if (readflags & HFILE_FAST && lasthist.text) {
 	    if (lasthist.fpos < lasthist.fsiz) {
-		fseek(in, lasthist.fpos, 0);
+		fseek(in, lasthist.fpos, SEEK_SET);
 		searching = 1;
 	    }
 	    else {
@@ -2741,7 +2741,7 @@ readhistfile(char *fn, int err, int readflags)
 		     && histstrcmp(pt, lasthist.text) == 0)
 			searching = 0;
 		    else {
-			fseek(in, 0, 0);
+			fseek(in, 0, SEEK_SET);
 			histfile_linect = 0;
 			searching = -1;
 		    }
diff --git a/Src/input.c b/Src/input.c
index e9989ffe4..f568cc135 100644
--- a/Src/input.c
+++ b/Src/input.c
@@ -495,9 +495,9 @@ stuff(char *fn)
 	zerr("can't open %s", fn);
 	return 1;
     }
-    fseek(in, 0, 2);
+    fseek(in, 0, SEEK_END);
     len = ftell(in);
-    fseek(in, 0, 0);
+    fseek(in, 0, SEEK_SET);
     buf = (char *)zalloc(len + 1);
     if (!(fread(buf, len, 1, in))) {
 	zerr("read error on %s", fn);
diff --git a/Src/watch.c b/Src/watch.c
index 93b3cb134..c41704315 100644
--- a/Src/watch.c
+++ b/Src/watch.c
@@ -169,9 +169,9 @@ getlogtime(WATCH_STRUCT_UTMP *u, int inout)
 	return u->ut_time;
     if (!(in = fopen(WATCH_WTMP_FILE, "r")))
 	return time(NULL);
-    fseek(in, 0, 2);
+    fseek(in, 0, SEEK_END);
     do {
-	if (fseek(in, ((first) ? -1 : -2) * sizeof(WATCH_STRUCT_UTMP), 1)) {
+	if (fseek(in, ((first) ? -1 : -2) * sizeof(WATCH_STRUCT_UTMP), SEEK_CUR)) {
 	    fclose(in);
 	    return time(NULL);
 	}