[llvm] [RISCV][TableGen] Generate RISCVTargetParser.inc from the new RISCVExtension tblgen information. (PR #89335)

[Francesco Petrogalli via llvm-commits]

================
@@ -10,115 +10,129 @@
 // RISC-V subtarget features and instruction predicates.
 //===----------------------------------------------------------------------===//
 
+class RISCVExtension<string n, int major, int minor, string f, string v,
+                     string d, list<RISCVExtension> i = []>
----------------
fpetrogalli wrote:

What if an extension needs to depend from a SubtargetFeature that is not a RISCV extension?

https://github.com/llvm/llvm-project/pull/89335