deps: merve: Don't include the vendored simdutf with --shared-simdutf

Different versions of simdutf may provide different implementations for
the same name, for example, the vendored version provides a symbol for
simdutf::find(),

simdutf_warn_unused const char *find(const char *start, const char *end,
                                     char character) noexcept;

while upstream simdutf 9.3.3 inlines it,

simdutf_warn_unused simdutf_really_inline simdutf_constexpr23 const char *
find(const char *start, const char *end, char character) noexcept {
    /* An inline function */
    ...
}

However, the vendored simdutf's headers are currently unconditionally
included for merve, regardless whether the shared simdutf is linked
against or not, leading to missing symbols at linking time like

mold: error: undefined symbol: simdutf::find(char const*, char const*, char)
>>> referenced by merve.cpp
>>>               obj/deps/merve/libmerve.a(obj/deps/merve/merve.merve.o):(lexer::CJSLexer::addReexport(std::__1::basic_string_view<char, std::__1::char_traits<char>>, unsigned int))
>>> referenced by merve.cpp
>>>               obj/deps/merve/libmerve.a(obj/deps/merve/merve.merve.o):(lexer::CJSLexer::addExport(std::__1::basic_string_view<char, std::__1::char_traits<char>>, unsigned int))

Do not include the vendored simdutf when compiling merve if shared
simdutf is used to ensure the headers match the linked library.

Signed-off-by: Yao Zi <me@ziyao.cc>

Author: ziyao233

deps/merve/merve.gyp

@@ -8,7 +8,6 @@
       'type': 'static_library',
       'include_dirs': [
         '.',
-        '../v8/third_party/simdutf',
       ],
       'direct_dependent_settings': {
         'include_dirs': ['.'],
@@ -29,6 +28,11 @@
             'CLANG_CXX_LANGUAGE_STANDARD': 'c++20',
           },
         }],
+        ['node_shared_simdutf=="false"', {
+          'include_dirs': [
+            '../v8/third_party/simdutf',
+          ],
+        }],
       ],
     },
   ]