sys: Declare 'end' as an extern char[]

While here, remove an unused declaration.

Reviewed by:	jrtc27
Sponsored by:	AFRL, DARPA
Differential Revision:	https://reviews.freebsd.org/D53898

sys/arm/arm/machdep.c

@@ -120,8 +120,6 @@ vm_offset_t vector_page;
 /* The address at which the kernel was loaded.  Set early in initarm(). */
 vm_paddr_t arm_physmem_kernaddr;
 
-extern int *end;
-
 #ifdef FDT
 vm_paddr_t pmap_pa;
 vm_offset_t systempage;

sys/arm/arm/machdep_boot.c

@@ -69,7 +69,7 @@
 static char static_kenv[4096];
 #endif
 
-extern int *end;
+extern char end[];
 
 static uint32_t board_revision;
 /* hex representation of uint64_t */

sys/arm64/arm64/machdep_boot.c

@@ -53,7 +53,7 @@
 #include <ddb/ddb.h>
 #endif
 
-extern int *end;
+extern char end[];
 static char *loader_envp;
 
 #ifdef FDT

sys/riscv/riscv/machdep.c

@@ -118,7 +118,7 @@ uint32_t boot_hart = BOOT_HART_INVALID;	/* The hart we booted on. */
 
 cpuset_t all_harts;
 
-extern int *end;
+extern char end[];
 
 static char static_kenv[PAGE_SIZE];