Fix control path where we have str as uninitialized string

| /home/ubuntu/work/oe/openembedded-core/build/tmp-musl/work/i586-oe-linux-musl/elfutils/0.164-r0/elfutils-0.164/libcpu/i386_disasm.c: In function 'i386_disasm':
| /home/ubuntu/work/oe/openembedded-core/build/tmp-musl/work/i586-oe-linux-musl/elfutils/0.164-r0/elfutils-0.164/libcpu/i386_disasm.c:310:5: error: 'str' may be used uninitialized in this function [-Werror=maybe-uninitialized]
|      memcpy (buf + bufcnt, _str, _len);           \
|      ^
| /home/ubuntu/work/oe/openembedded-core/build/tmp-musl/work/i586-oe-linux-musl/elfutils/0.164-r0/elfutils-0.164/libcpu/i386_disasm.c:709:17: note: 'str' was declared here
|      const char *str;

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Upstream-Status: Pending
Index: elfutils-0.164/libcpu/i386_disasm.c
===================================================================
--- elfutils-0.164.orig/libcpu/i386_disasm.c
+++ elfutils-0.164/libcpu/i386_disasm.c
@@ -821,6 +821,7 @@ i386_disasm (const uint8_t **startp, con
 			    }
 
 			default:
+			  str = "";
 			  assert (! "INVALID not handled");
 			}
 		    }