Use bitwise OR with mask for sign extension

Sign extend using bitwise OR with mask, instead of unary minus.
Fixes error when building for UWP with Security Development Lifecycle (SDL).
See https://learn.microsoft.com/en-us/cpp/build/reference/sdl-enable-additional-security-checks?view=msvc-170

arch/SH/SHDisassembler.c

@@ -1459,13 +1459,13 @@ static bool decode_long(uint32_t code, uint64_t address, MCInst *MI,
 		if (code & 0x00010000) {
 			// movi20s #imm,
 			imm <<= 8;
-			if (imm >= 1 << 27)
-				imm = -((1 << 28) - imm);
+			if (imm & (1 << (28 - 1)))
+				imm |= ~((1 << 28) - 1);
 			insn = SH_INS_MOVI20S;
 		} else {
 			// MOVI20
-			if (imm >= 1 << 19)
-				imm = -((1 << 20) - imm);
+			if (imm & (1 << (28 - 1)))
+				imm |= ~((1 << 20) - 1);
 			insn = SH_INS_MOVI20;
 		}
 		set_imm(info, 0, imm);