[mlir] Add lib to tests for shared build (llvm#88574)

These resulted in link failures:

```
/usr/bin/ld:
tools/mlir/test/CAPI/CMakeFiles/mlir-capi-translation-test.dir/translation.c.o:
in function `main':
translation.c:(.text.main+0x58): undefined reference to
`LLVMContextCreate'
/usr/bin/ld: translation.c:(.text.main+0x9b): undefined reference to
`LLVMDumpModule'
/usr/bin/ld: translation.c:(.text.main+0xa3): undefined reference to
`LLVMDisposeModule'
/usr/bin/ld: translation.c:(.text.main+0xb3): undefined reference to
`LLVMContextDispose'
```

Found in mlir-hs. Not sure why this hasn't been flagged elsewhere.

Author: jpienaar

mlir/test/CAPI/CMakeLists.txt

@@ -12,6 +12,7 @@ function(_add_capi_test_executable name)
   llvm_update_compile_flags(${name})
   if(MLIR_BUILD_MLIR_C_DYLIB)
     target_link_libraries(${name} PRIVATE
+      LLVMCore
       MLIR-C)
   else()
     target_link_libraries(${name} PRIVATE