[RISC-V] Disable corelib crossgen2 (#84781)

Author: clamp03

src/coreclr/crossgen-corelib.proj

@@ -16,6 +16,7 @@
       <CrossDir Condition="'$(CrossBuild)' == 'true' or '$(BuildArchitecture)' != '$(TargetArchitecture)'">$(BuildArchitecture)</CrossDir>
 
       <BuildDll>true</BuildDll>
+      <BuildDll Condition="'$(TargetArchitecture)' == 'riscv64'">false</BuildDll>
 
       <BuildPdb>false</BuildPdb>
       <BuildPdb Condition="$(BuildDll) and '$(OS)' == 'Windows_NT' and '$(TargetOS)' == 'windows'">true</BuildPdb>