[libc] wcscspn implementation (#146158)

Implemented wcscspn and tests.

---------

Co-authored-by: Sriya Pratipati <sriyap@google.com>

utils/bazel/llvm-project-overlay/libc/BUILD.bazel

@@ -5815,6 +5815,18 @@ libc_function(
     ],
 )
 
+libc_function(
+    name = "wcscspn",
+    srcs = ["src/wchar/wcscspn.cpp"],
+    hdrs = ["src/wchar/wcscspn.h"],
+    deps = [
+        ":__support_common",
+        ":__support_macros_config",
+        ":types_size_t",
+        ":types_wchar_t",
+    ],
+)
+
 libc_function(
     name = "wcslen",
     srcs = ["src/wchar/wcslen.cpp"],

utils/bazel/llvm-project-overlay/libc/test/src/wchar/BUILD.bazel

@@ -73,6 +73,16 @@ libc_test(
     ],
 )
 
+libc_test(
+    name = "wcscspn_test",
+    srcs = ["wcscspn_test.cpp"],
+    deps = [
+        "//libc:types_size_t",
+        "//libc:types_wchar_t",
+        "//libc:wcscspn",
+    ],
+)
+
 libc_test(
     name = "wcslen_test",
     srcs = ["wcslen_test.cpp"],