Rewrote the instruction decoder code-generator.

- Reduced amount of C++ code generated for instruction decoding (40-50%)
- Significantly improves compile time of the generated decoders (up to 80%)

PiperOrigin-RevId: 698135815
Change-Id: Ia916bea00d1bac3b6a8ca736f7d1036868e49557

riscv/riscv32_decoder.cc

diff --git a/riscv/riscv32_decoder.cc b/riscv/riscv32_decoder.cc
index 57e9c64..6766049 100644
--- a/riscv/riscv32_decoder.cc
+++ b/riscv/riscv32_decoder.cc
@@ -15,7 +15,6 @@
 #include "riscv/riscv32_decoder.h"
 
 #include <cstdint>
-#include <new>
 #include <string>
 
 #include "mpact/sim/generic/instruction.h"