Kernel/LibC: Implement `creat` with `open`

This allows getting rid of unnecessary SYS_CREATE. Directory creation
still has its own syscall, but I could combine it with SYS_OPEN also.

kernel/include/kernel/Process.h

@@ -109,7 +109,6 @@ namespace Kernel
 		BAN::ErrorOr<long> sys_read(int fd, void* buffer, size_t count);
 		BAN::ErrorOr<long> sys_write(int fd, const void* buffer, size_t count);
 		BAN::ErrorOr<long> sys_access(const char* path, int amode);
-		BAN::ErrorOr<long> sys_create(const char*, mode_t);
 		BAN::ErrorOr<long> sys_create_dir(const char*, mode_t);
 		BAN::ErrorOr<long> sys_unlink(const char*);
 		BAN::ErrorOr<long> readlink_impl(BAN::RefPtr<Inode>, char* buffer, size_t bufsize);

kernel/kernel/Process.cpp

@@ -970,14 +970,6 @@ namespace Kernel
 		return 0;
 	}
 
-	BAN::ErrorOr<long> Process::sys_create(const char* path, mode_t mode)
-	{
-		LockGuard _(m_process_lock);
-		TRY(validate_string_access(path));
-		TRY(create_file_or_dir(VirtualFileSystem::get().root_file(), path, mode));
-		return 0;
-	}
-
 	BAN::ErrorOr<long> Process::sys_create_dir(const char* path, mode_t mode)
 	{
 		LockGuard _(m_process_lock);

userspace/libraries/LibC/fcntl.cpp

@@ -1,12 +1,11 @@
 #include <fcntl.h>
-#include <errno.h>
 #include <stdarg.h>
 #include <sys/syscall.h>
 #include <unistd.h>
 
 int creat(const char* path, mode_t mode)
 {
-	return syscall(SYS_CREATE, path, S_IFREG | __UMASKED_MODE(mode));
+	return open(path, O_WRONLY | O_CREAT | O_TRUNC, mode);
 }
 
 int open(const char* path, int oflag, ...)

userspace/libraries/LibC/include/sys/syscall.h

@@ -56,7 +56,6 @@ __BEGIN_DECLS
 	O(SYS_POWEROFF,			poweroff)		\
 	O(SYS_CHMOD,			chmod)			\
 	O(SYS_FCHMOD,			fchmod)			\
-	O(SYS_CREATE,			create)			\
 	O(SYS_CREATE_DIR,		create_dir)		\
 	O(SYS_UNLINK,			unlink) 		\
 	O(SYS_READLINK,			readlink)		\