cgen: do not generate unnecessary memdup() definition

vlib/builtin/builtin.c.v

@@ -605,6 +605,7 @@ pub fn free(ptr voidptr) {
 // returns a pointer to the newly allocated space.
 [unsafe]
 pub fn memdup(src voidptr, sz int) voidptr {
+	// pub fn memdup(src voidptr, sz isize) voidptr {
 	$if trace_memdup ? {
 		C.fprintf(C.stderr, c'memdup size: %10d\n', sz)
 	}
@@ -619,6 +620,7 @@ pub fn memdup(src voidptr, sz int) voidptr {
 
 [unsafe]
 pub fn memdup_noscan(src voidptr, sz int) voidptr {
+	// pub fn memdup_noscan(src voidptr, sz isize) voidptr {
 	$if trace_memdup ? {
 		C.fprintf(C.stderr, c'memdup_noscan size: %10d\n', sz)
 	}
@@ -636,7 +638,7 @@ pub fn memdup_noscan(src voidptr, sz int) voidptr {
 // memdup_uncollectable then copies the contents of `src` into the allocated
 // space and returns a pointer to the newly allocated space.
 [unsafe]
-pub fn memdup_uncollectable(src voidptr, sz int) voidptr {
+pub fn memdup_uncollectable(src voidptr, sz isize) voidptr {
 	$if trace_memdup ? {
 		C.fprintf(C.stderr, c'memdup_uncollectable size: %10d\n', sz)
 	}

vlib/v/gen/c/cgen.v

@@ -1004,6 +1004,9 @@ fn (mut g Gen) base_type(_t ast.Type) string {
 			return 'u64'
 		}
 	}
+	if t == ast.int_type {
+		//return 'i64'
+	}
 	share := t.share()
 	mut styp := if share == .atomic_t { t.atomic_typename() } else { g.cc_type(t, true) }
 	if t.has_flag(.shared_f) {

vlib/v/gen/c/cheaders.v

@@ -523,7 +523,7 @@ void _vcleanup(void);
 #define _ARR_LEN(a) ( (sizeof(a)) / (sizeof(a[0])) )
 
 void v_free(voidptr ptr);
-voidptr memdup(voidptr src, int sz);
+//voidptr memdup(voidptr src, isize sz);
 
 #if INTPTR_MAX == INT32_MAX
 	#define TARGET_IS_32BIT 1