[libc][bazel] Add Bazel rules for rand/srand functions. (#159617)

These functions are unlikely to be used in the overlay mode (since they are stateful), but it's worth verifying the correctness of underlying RNG (which may be reused in other places) in Bazel build regardless.

Author: vonosmas

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

@@ -278,6 +278,14 @@ libc_support_library(
     hdrs = ["hdr/stdio_overlay.h"],
 )
 
+libc_support_library(
+    name = "hdr_stdlib_macros",
+    hdrs = ["hdr/stdlib_macros.h"],
+    deps = [
+        ":hdr_stdlib_overlay",
+    ],
+)
+
 libc_support_library(
     name = "hdr_stdlib_overlay",
     hdrs = ["hdr/stdlib_overlay.h"],
@@ -5066,6 +5074,41 @@ libc_function(
     ],
 )
 
+libc_support_library(
+    name = "rand_util",
+    srcs = ["src/stdlib/rand_util.cpp"],
+    hdrs = ["src/stdlib/rand_util.h"],
+    deps = [
+        ":__support_cpp_atomic",
+        ":__support_macros_attributes",
+        ":__support_macros_config",
+    ],
+)
+
+libc_function(
+    name = "rand",
+    srcs = ["src/stdlib/rand.cpp"],
+    hdrs = ["src/stdlib/rand.h"],
+    deps = [
+        ":__support_common",
+        ":__support_macros_config",
+        ":__support_threads_sleep",
+        ":hdr_stdlib_macros",
+        ":rand_util",
+    ],
+)
+
+libc_function(
+    name = "srand",
+    srcs = ["src/stdlib/srand.cpp"],
+    hdrs = ["src/stdlib/srand.h"],
+    deps = [
+        ":__support_common",
+        ":__support_macros_config",
+        ":rand_util",
+    ],
+)
+
 libc_support_library(
     name = "str_from_util",
     hdrs = ["src/stdlib/str_from_util.h"],

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

@@ -159,6 +159,15 @@ libc_test(
     ],
 )
 
+libc_test(
+    name = "rand_test",
+    srcs = ["rand_test.cpp"],
+    deps = [
+        "//libc:rand",
+        "//libc:srand",
+    ],
+)
+
 libc_test_library(
     name = "strfrom_test_helper",
     hdrs = ["StrfromTest.h"],