SERVER-80619 update bazel cc_binary definition to use tcmalloc conditionally

buildscripts/bazel_testbuilds/unit_test.cpp

@@ -1,8 +1,20 @@
 // C++ compilation file used for testing bazel compilation.
 
+#include <dlfcn.h>
 #include <iostream>
 
 int main() {
-    printf("Hello World!\n");
+    void* tcmalloc_so = dlopen(
+        "/home/ubuntu/mongo/bazel-bin/_solib_arm64/"
+        "libsrc_Sthird_Uparty_Sgperftools_Slibtcmalloc_Uminimal.so",
+        RTLD_NOW);
+    void* tcmalloc = dlsym(tcmalloc_so, "malloc");
+
+    void* libcmalloc_so = dlopen("/lib/aarch64-linux-gnu/libc.so.6", RTLD_NOW);
+    void* libcmalloc = dlsym(libcmalloc_so, "malloc");
+
+    printf("%p [unit test malloc]\n", malloc);
+    printf("%p [tcmalloc]\n", tcmalloc);
+    printf("%p [libc malloc]\n", libcmalloc);
     return 0;
 }