Use argv_array in place of vector

Instead of using our own vector implementation, use argv_array from Git
which has been specifically designed for dynamic size argv arrays.

Drop vector.h and vector.c which are no longer needed.

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>

cgit.mk

@@ -50,7 +50,6 @@ CGIT_OBJ_NAMES += ui-stats.o
 CGIT_OBJ_NAMES += ui-summary.o
 CGIT_OBJ_NAMES += ui-tag.o
 CGIT_OBJ_NAMES += ui-tree.o
-CGIT_OBJ_NAMES += vector.o
 
 CGIT_OBJS := $(addprefix $(CGIT_PREFIX),$(CGIT_OBJ_NAMES))