[PATCH] Fix -Wmaybe-uninitialized warning in opcodes/i386-dis.c

[Tom Tromey <tromey@adacore.com>]

A recent change in opcodes/i386-dis.c caused a build failure on my
x86-64 Fedora 36 system:

../../binutils-gdb/opcodes/i386-dis.c: In function ‘OP_J’:
../../binutils-gdb/opcodes/i386-dis.c:12705:22: error: ‘val’ may be used uninitialized [-Werror=maybe-uninitialized]
12705 |           disp = val & 0x8000 ? val - 0x10000 : val;
      |                  ~~~~^~~~~~~~

This patch fixes the warning, but I don't know whether it's really
correct -- I just copied a pattern from eariler in this function.

opcodes/ChangeLog
2023-04-21  Tom Tromey  <tromey@adacore.com>

	* i386-dis.c (OP_J): Check result of get16.
---
 opcodes/ChangeLog  | 4 ++++
 opcodes/i386-dis.c | 3 ++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/opcodes/i386-dis.c b/opcodes/i386-dis.c
index 46ba01fe093..f021bdaa3e7 100644
--- a/opcodes/i386-dis.c
+++ b/opcodes/i386-dis.c
@@ -12701,7 +12701,8 @@ OP_J (instr_info *ins, int bytemode, int sizeflag)
 	{
 	  int val;
 
-	  get16 (ins, &val);
+	  if (!get16 (ins, &val))
+	    return false;
 	  disp = val & 0x8000 ? val - 0x10000 : val;
 	  /* In 16bit mode, address is wrapped around at 64k within
 	     the same segment.  Otherwise, a data16 prefix on a jump
-- 
2.39.1