Hexagon: fix build errors

Fix type-o in ptrace.c.
Add missing include: asm/hexagon_vm.h
Remove superfluous cast.
Replace 'p3_0' with 'preds'.

Signed-off-by: Sid Manning <sidneym@codeaurora.org>
Add -mlong-calls to build flags.
Signed-off-by: Brian Cain <bcain@codeaurora.org>

Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
diff --git a/arch/hexagon/Makefile b/arch/hexagon/Makefile
index c168c69..3826483 100644
--- a/arch/hexagon/Makefile
+++ b/arch/hexagon/Makefile
@@ -10,6 +10,9 @@
 # Do not use single-byte enums; these will overflow.
 KBUILD_CFLAGS += -fno-short-enums
 
+# We must use long-calls:
+KBUILD_CFLAGS += -mlong-calls
+
 # Modules must use either long-calls, or use pic/plt.
 # Use long-calls for now, it's easier.  And faster.
 # KBUILD_CFLAGS_MODULE += -fPIC