cgit.c: Use "else" for mutually exclusive branches

When parsing command line arguments, no pair of command line options can
ever match simultaneously. Use "else if" blocks to reflect this. This
change improves both readability and speed.

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>
diff --git a/cgit.c b/cgit.c
index e31962d..f4262d8 100644
--- a/cgit.c
+++ b/cgit.c
@@ -865,35 +865,26 @@
 	for (i = 1; i < argc; i++) {
 		if (!prefixcmp(argv[i], "--cache=")) {
 			ctx.cfg.cache_root = xstrdup(argv[i] + 8);
-		}
-		if (!strcmp(argv[i], "--nocache")) {
+		} else if (!strcmp(argv[i], "--nocache")) {
 			ctx.cfg.nocache = 1;
-		}
-		if (!strcmp(argv[i], "--nohttp")) {
+		} else if (!strcmp(argv[i], "--nohttp")) {
 			ctx.env.no_http = "1";
-		}
-		if (!prefixcmp(argv[i], "--query=")) {
+		} else if (!prefixcmp(argv[i], "--query=")) {
 			ctx.qry.raw = xstrdup(argv[i] + 8);
-		}
-		if (!prefixcmp(argv[i], "--repo=")) {
+		} else if (!prefixcmp(argv[i], "--repo=")) {
 			ctx.qry.repo = xstrdup(argv[i] + 7);
-		}
-		if (!prefixcmp(argv[i], "--page=")) {
+		} else if (!prefixcmp(argv[i], "--page=")) {
 			ctx.qry.page = xstrdup(argv[i] + 7);
-		}
-		if (!prefixcmp(argv[i], "--head=")) {
+		} else if (!prefixcmp(argv[i], "--head=")) {
 			ctx.qry.head = xstrdup(argv[i] + 7);
 			ctx.qry.has_symref = 1;
-		}
-		if (!prefixcmp(argv[i], "--sha1=")) {
+		} else if (!prefixcmp(argv[i], "--sha1=")) {
 			ctx.qry.sha1 = xstrdup(argv[i] + 7);
 			ctx.qry.has_sha1 = 1;
-		}
-		if (!prefixcmp(argv[i], "--ofs=")) {
+		} else if (!prefixcmp(argv[i], "--ofs=")) {
 			ctx.qry.ofs = atoi(argv[i] + 6);
-		}
-		if (!prefixcmp(argv[i], "--scan-tree=") ||
-		    !prefixcmp(argv[i], "--scan-path=")) {
+		} else if (!prefixcmp(argv[i], "--scan-tree=") ||
+		           !prefixcmp(argv[i], "--scan-path=")) {
 			/* HACK: the global snapshot bitmask defines the
 			 * set of allowed snapshot formats, but the config
 			 * file hasn't been parsed yet so the mask is