[next] SH: Use bitwise OR with mask for sign extension (#2389)

* 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

* Remove unused store

Remove unused store caught by clang-tidy.

* Suppress clang-tidy false positive

Ignore an unitialized va_list false positive emitted by clang-tidy

---------

Co-authored-by: Wu ChenXu <kabeor00@gmail.com>

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);