ast: fix arch loongarch64 comptime support (fix #24906) (#24907)

vlib/v/ast/comptime_valid_idents.v

@@ -5,7 +5,7 @@ pub const valid_comptime_if_os = ['windows', 'ios', 'macos', 'mach', 'darwin', '
 	'haiku', 'serenity', 'vinix', 'plan9', 'wasm32_emscripten']
 pub const valid_comptime_if_compilers = ['gcc', 'tinyc', 'clang', 'mingw', 'msvc', 'cplusplus']
 pub const valid_comptime_if_platforms = ['amd64', 'i386', 'aarch64', 'arm64', 'arm32', 'rv64',
-	'rv32', 's390x', 'ppc64le']
+	'rv32', 's390x', 'ppc64le', 'loongarch64']
 pub const valid_comptime_if_cpu_features = ['x64', 'x32', 'little_endian', 'big_endian']
 pub const valid_comptime_if_other = ['apk', 'js', 'debug', 'prod', 'test', 'glibc', 'prealloc',
 	'no_bounds_checking', 'freestanding', 'threads', 'js_node', 'js_browser', 'js_freestanding',

vlib/v/tests/comptime/comptime_arch_test.v

@@ -0,0 +1,28 @@
+const arch = $if amd64 {
+	'amd64'
+} $else $if i386 {
+	'i386'
+}
+//$else $if aarch64 {'aarch64'}
+$else $if arm64 {
+	'arm64'
+} $else $if arm32 {
+	'arm32'
+} $else $if rv64 {
+	'rv64'
+} $else $if rv32 {
+	'rv32'
+} $else $if s390x {
+	's390x'
+} $else $if ppc64le {
+	'ppc64le'
+} $else $if loongarch64 {
+	'loongarch64'
+} $else {
+	'unknown'
+}
+
+fn test_main() {
+	println('arch is ${arch}')
+	assert arch != 'unknown'
+}