Fix warnings.

lib/zip_source_file_common.c

diff --git a/lib/zip_source_file_common.c b/lib/zip_source_file_common.c
index 977d390..74e2100 100644
--- a/lib/zip_source_file_common.c
+++ b/lib/zip_source_file_common.c
@@ -54,7 +54,6 @@
     zip_source_file_context_t *ctx;
     zip_source_t *zs;
     zip_source_file_stat_t sb;
-    bool stat_valid;
 
     if (ops == NULL) {
 	zip_error_set(error, ZIP_ER_INVAL, 0);

lib/zip_source_file_win32_ansi.c

diff --git a/lib/zip_source_file_win32_ansi.c b/lib/zip_source_file_win32_ansi.c
index 19ceba6..1869a12 100644
--- a/lib/zip_source_file_win32_ansi.c
+++ b/lib/zip_source_file_win32_ansi.c
@@ -34,7 +34,7 @@
 #include "zip_source_file_win32.h"
 
 static char *ansi_allocate_tempname(const char *name, size_t extra_chars, size_t *lengthp);
-static void ansi_make_tempname(char *buf, size_t len, const char *name, int i);
+static void ansi_make_tempname(char *buf, size_t len, const char *name, zip_uint32_t i);
 
 zip_source_file_win32_write_operations_t ops_ansi = {
     ansi_allocate_tempname,

lib/zip_source_file_win32_utf16.c

diff --git a/lib/zip_source_file_win32_utf16.c b/lib/zip_source_file_win32_utf16.c
index b77ef43..9ada4af 100644
--- a/lib/zip_source_file_win32_utf16.c
+++ b/lib/zip_source_file_win32_utf16.c
@@ -38,7 +38,7 @@
 static BOOL utf16_delete_file(const char *name);
 static DWORD utf16_get_file_attributes(const char *name);
 static BOOL utf16_get_file_attributes_ex(const char *name, GET_FILEEX_INFO_LEVELS info_level, void *information);
-static void utf16_make_tempname(char *buf, size_t len, const char *name, int i);
+static void utf16_make_tempname(char *buf, size_t len, const char *name, zip_uint32_t i);
 static BOOL utf16_move_file(const char *from, const char *to, DWORD flags);
 static BOOL utf16_set_file_attributes(const char *name, DWORD attributes);
 static char *utf16_strdup(const char *string);