We basically follow the instructions in this link to enable FIPS mode.
How can I make RHEL 6 or RHEL 7 FIPS 140-2 compliant?

And we seem to have succeeded because

$ sysctl crypto.fips_enabled
crypto.fips_enabled = 1

And calling FIPS_mode_set(1) returns 1, which means success.

Quote from OpenSSL wiki:
Random Numbers

To use the FIPS random number generator, simply use RAND_bytes as described earlier. Note that the call to FIPS_mode_set must succeed in order to operate in FIPS 140 mode.

However, I run this code:

#include <stdio.h>
#include <openssl/crypto.h>
#include <openssl/rand.h>
int main()
{
    unsigned char buffer[4];
    int rc;

    rc = FIPS_mode_set(1);
    printf("FIPS_mode_set rc=%d\n", rc);
    rc = RAND_bytes(buffer, sizeof(buffer));
    printf("RAND_bytes rc=%d random number=%08X\n", rc, *(int *)buffer);
    rc = FIPS_rand_bytes(buffer, sizeof(buffer));
    printf("FIPS_rand_bytes rc=%d random number=%08X\n", rc, *(int *)buffer);
    return 0;
}

And I patched the RAND_bytes() and FIPS_rand_bytes() in openssl-1.0.1e to let them print their function names.
I found they are still called separately.

I thought RAND_bytes() will automatically be mapped to FIPS_rand_bytes().
Is my assumption wrong?
How do I know we are really using the FIPS version of functions.