Fix warnings with recent versions of GCC.

This is a combination of these commits:

  https://github.com/openbios/openbios/commit/14be7d187a327a89c068c4e2551d5012a3c25703
  https://github.com/openbios/openbios/commit/0e6b8b3cb4a25a4680f238bae76de5e370e706c8
  https://github.com/openbios/openbios/commit/51067854a7606cceb8b1e0a3d2108da69ff46973

...with minor adaptations to apply on 1.1.


diff --git a/arch/sparc32/context.c b/arch/sparc32/context.c
--- a/arch/sparc32/context.c
+++ b/arch/sparc32/context.c
@@ -86,7 +86,7 @@ struct context *switch_to(struct context *ctx)
     __context = ctx;
     asm __volatile__ ("\n\tcall __switch_context"
                       "\n\tnop" ::: "g1", "g2", "g3", "g4", "g5", "g6", "g7",
-                      "o0", "o1", "o2", "o3", "o4", "o5", "sp", "o7",
+                      "o0", "o1", "o2", "o3", "o4", "o5", "o7",
                       "l0", "l1", "l2", "l3", "l4", "l5", "l6", "l7",
                       "i0", "i1", "i2", "i3", "i4", "i5", "i7",
                       "f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7", "f8", "f9",
diff --git a/drivers/cuda.c b/drivers/cuda.c
--- a/drivers/cuda.c
+++ b/drivers/cuda.c
@@ -355,7 +355,7 @@ static void
 rtc_init(char *path)
 {
 	phandle_t ph, aliases;
-	char buf[64];
+	char buf[128];
 
         snprintf(buf, sizeof(buf), "%s/rtc", path);
 	REGISTER_NAMED_NODE(rtc, buf);
diff --git a/drivers/ide.c b/drivers/ide.c
--- a/drivers/ide.c
+++ b/drivers/ide.c
@@ -987,7 +987,7 @@ ob_ide_identify_drive(struct ide_drive *drive)
 		drive->sect = id.sectors;
 	}
 
-	strncpy(drive->model, (char*)id.model, sizeof(id.model));
+	strncpy(drive->model, (char*)id.model, sizeof(drive->model));
 	drive->model[40] = '\0';
 	return 0;
 }
diff --git a/fs/hfs/hfs_fs.c b/fs/hfs/hfs_fs.c
--- a/fs/hfs/hfs_fs.c
+++ b/fs/hfs/hfs_fs.c
@@ -86,7 +86,7 @@ _search( hfsvol *vol, const char *path, const char *sname, hfsfile **ret_fd )
 
 	strncpy( buf, path, sizeof(buf) );
 	if( buf[strlen(buf)-1] != ':' )
-		strncat( buf, ":", sizeof(buf) );
+		strncat( buf, ":", sizeof(buf) - 1 );
 	buf[sizeof(buf)-1] = 0;
 	p = buf + strlen( buf );
 
@@ -101,7 +101,7 @@ _search( hfsvol *vol, const char *path, const char *sname, hfsfile **ret_fd )
 		*p = 0;
 		topdir = 0;
 
-		strncat( buf, ent.name, sizeof(buf) );
+		strncat( buf, ent.name, sizeof(buf) - 1);
 		if( (status=_search(vol, buf, sname, ret_fd)) != 2 )
 			continue;
 		topdir = 1;
diff --git a/libc/string.c b/libc/string.c
--- a/libc/string.c
+++ b/libc/string.c
@@ -349,10 +349,7 @@ int memcmp(const void * cs,const void * ct,size_t count)
 char *
 strdup( const char *str )
 {
-	char *p;
-	if( !str )
-		return NULL;
-	p = malloc( strlen(str) + 1 );
+	char *p = malloc( strlen(str) + 1 );
 	strcpy( p, str );
 	return p;
 }
diff --git a/packages/nvram.c b/packages/nvram.c
--- a/packages/nvram.c
+++ b/packages/nvram.c
@@ -105,7 +105,7 @@ create_free_part( char *ptr, int size )
 	nvpart_t *nvp = (nvpart_t*)ptr;
 	memset( nvp, 0, size );
 
-	strncpy( nvp->name, "777777777777", sizeof(nvp->name) );
+	strncpy( nvp->name, "77777777777", sizeof(nvp->name) );
 	nvp->signature = NV_SIG_FREE;
 	nvp->len_hi = (size /16) >> 8;
 	nvp->len_lo = size /16;