tests/disassembler: Use negative offsets in disassembler tests

We recently fixed a bug in negative offsets handling in the
disassembler. Let's use a few negative offsets in the tests to make sure
we support them.

tests/disassembler.rs

@@ -250,9 +250,9 @@ jle r1, r2, +0x3
 jset r1, r2, +0x3
 jne r1, r2, +0x3
 jsgt r1, r2, +0x3
-jsge r1, r2, +0x3
+jsge r1, r2, -0x3
 jslt r1, r2, +0x3
-jsle r1, r2, +0x3");
+jsle r1, r2, -0x3");
 
     disasm!("jeq r1, 0x2, +0x3
 jgt r1, 0x2, +0x3
@@ -262,9 +262,9 @@ jle r1, 0x2, +0x3
 jset r1, 0x2, +0x3
 jne r1, 0x2, +0x3
 jsgt r1, 0x2, +0x3
-jsge r1, 0x2, +0x3
+jsge r1, 0x2, -0x3
 jslt r1, 0x2, +0x3
-jsle r1, 0x2, +0x3");
+jsle r1, 0x2, -0x3");
 }
 
 // Test all supported Endian mnemonics.