Kernel+LibC+Userland: Switch to 64-bit time_t

Let's not have that 2038 problem people are talking about. :^)

Kernel/FileSystem/DiskBackedFileSystem.cpp

@@ -33,7 +33,7 @@
 //#define DBFS_DEBUG
 
 struct CacheEntry {
-    u32 timestamp { 0 };
+    time_t timestamp { 0 };
     u32 block_index { 0 };
     u8* data { nullptr };
     bool has_data { false };

Kernel/UnixTypes.h

@@ -294,7 +294,7 @@ struct sigaction {
 #define OFF_T_MAX 2147483647
 
 typedef i32 off_t;
-typedef u32 time_t;
+typedef i64 time_t;
 
 struct utimbuf {
     time_t actime;

Libraries/LibC/sys/types.h

@@ -56,7 +56,7 @@ typedef uint16_t mode_t;
 typedef uint32_t nlink_t;
 typedef uint32_t blksize_t;
 typedef uint32_t blkcnt_t;
-typedef uint32_t time_t;
+typedef int64_t time_t;
 typedef uint32_t useconds_t;
 typedef int32_t suseconds_t;
 typedef uint32_t clock_t;

Libraries/LibC/time.h

@@ -49,7 +49,7 @@ extern char* tzname[2];
 extern int daylight;
 
 typedef uint32_t clock_t;
-typedef uint32_t time_t;
+typedef int64_t time_t;
 
 struct tm* localtime(const time_t*);
 struct tm* gmtime(const time_t*);

Userland/date.cpp

@@ -33,7 +33,7 @@ int main(int argc, char** argv)
     time_t now = time(nullptr);
 
     if (argc == 2 && !strcmp(argv[1], "-u")) {
-        printf("%u\n", now);
+        printf("%lld\n", now);
         return 0;
     }