Fix all current build warnings in the userland.

Userland/date.cpp

@@ -1,8 +1,10 @@
 #include <LibC/time.h>
 #include <LibC/stdio.h>
 
-int main(int c, char** v)
+int main(int argc, char** argv)
 {
+    (void) argc;
+    (void) argv;
     time_t now = time(nullptr);
     printf("%u\n", now);
     return 0;

Userland/ft.cpp

@@ -3,6 +3,8 @@
 
 int main(int argc, char** argv)
 {
+    (void) argc;
+    (void) argv;
     printf("Testing fork()...\n");
     pid_t pid = fork();
     if (!pid) {

Userland/ft2.cpp

@@ -3,6 +3,8 @@
 
 int main(int argc, char** argv)
 {
+    (void) argc;
+    (void) argv;
     printf("Testing fork()...\n");
     pid_t pid = fork();
     if (!pid) {

Userland/hostname.cpp

@@ -1,10 +1,12 @@
-#include <LibC/unistd.h>
-#include <LibC/stdio.h>
-#include <LibC/errno.h>
-#include <LibC/string.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
 
-int main(int c, char** v)
+int main(int argc, char** argv)
 {
+    (void) argc;
+    (void) argv;
     char buffer[HOST_NAME_MAX];
     int rc = gethostname(buffer, sizeof(buffer));
     if (rc < 0) {

Userland/id.cpp

@@ -4,8 +4,10 @@
 #include <grp.h>
 #include <alloca.h>
 
-int main(int c, char** v)
+int main(int argc, char** argv)
 {
+    (void) argc;
+    (void) argv;
     uid_t uid = getuid();
     gid_t gid = getgid();
 

Userland/ls.cpp

@@ -4,8 +4,10 @@
 #include <LibC/errno.h>
 #include <LibC/string.h>
 
-int main(int c, char** v)
+int main(int argc, char** argv)
 {
+    (void) argc;
+    (void) argv;
     bool colorize = true;
 
     DIR* dirp = opendir(".");

Userland/mm.cpp

@@ -1,8 +1,10 @@
 #include <LibC/stdio.h>
 #include <LibC/unistd.h>
 
-int main(int c, char** v)
+int main(int argc, char** argv)
 {
+    (void) argc;
+    (void) argv;
     int fd = open("/proc/mm", O_RDONLY);
     if (fd == -1) {
         perror("failed to open /proc/mm");

Userland/ps.cpp

@@ -1,8 +1,10 @@
 #include <LibC/stdio.h>
 #include <LibC/unistd.h>
 
-int main(int c, char** v)
+int main(int argc, char** argv)
 {
+    (void) argc;
+    (void) argv;
     int fd = open("/proc/summary", O_RDONLY);
     if (fd == -1) {
         perror("failed to open /proc/summary");

Userland/sh.cpp

@@ -1,11 +1,11 @@
-#include <LibC/stdio.h>
-#include <LibC/unistd.h>
-#include <LibC/process.h>
-#include <LibC/errno.h>
-#include <LibC/string.h>
-#include <LibC/stdlib.h>
-#include <LibC/utsname.h>
-#include <LibC/pwd.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <process.h>
+#include <errno.h>
+#include <string.h>
+#include <stdlib.h>
+#include <utsname.h>
+#include <pwd.h>
 #include <sys/mman.h>
 #include <signal.h>
 #include <AK/FileSystemPath.h>
@@ -43,7 +43,7 @@ void did_receive_signal(int signum)
     g_got_signal = true;
 }
 
-void handle_sigint(int signum)
+void handle_sigint(int)
 {
     printf("Interrupt received by sh\n");
 }
@@ -105,7 +105,7 @@ static int sh_wt(int, const char**)
 {
     const char* rodata_ptr = "foo";
     printf("Writing to rodata=%p...\n", rodata_ptr);
-    *(char*)rodata_ptr = 0;
+    *const_cast<char*>(rodata_ptr) = 0;
 
     char* text_ptr = (char*)sh_fef;
     printf("Writing to text=%p...\n", text_ptr);
@@ -141,7 +141,6 @@ close_it:
 
 static int sh_mp(int, const char**)
 {
-    int rc;
     int fd = open("/kernel.map", O_RDONLY);
     if (fd < 0) {
         perror("open(/kernel.map)");

Userland/tst.cpp

@@ -2,6 +2,8 @@
 
 int main(int argc, char** argv)
 {
+    (void) argc;
+    (void) argv;
     printf("Counting to 100000: \033[s");
     for (unsigned i = 0; i <= 100000; ++i) {
         printf("\033[u\033[s%u", i);

Userland/tty.cpp

@@ -1,5 +1,5 @@
-#include <LibC/stdio.h>
-#include <LibC/unistd.h>
+#include <stdio.h>
+#include <unistd.h>
 
 int main(int, char**)
 {

Userland/uname.cpp

@@ -1,5 +1,5 @@
-#include <LibC/utsname.h>
-#include <LibC/stdio.h>
+#include <utsname.h>
+#include <stdio.h>
 
 int main(int argc, char** argv)
 {