Remove some stale ifdefs from urandom.cc

After 53f09ad241ddf7e37a426a5e3c6dfa6d4dca9706, we use getentropy on
FreeBSD, so the FREEBSD_GETRANDOM check is dead code. urandom.cc can
assume OPENSSL_LINUX is true and include headers accordingly.

We also no longer do the ioctl dance on /dev/urandom in BORINGSSL_FIPS,
so includes for those can be removed.

Change-Id: I394b43ffc05a1ccd1759aac1277e2a2971eddb67
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/82107
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
Auto-Submit: David Benjamin <davidben@google.com>

crypto/rand/urandom.cc

diff --git a/crypto/rand/urandom.cc b/crypto/rand/urandom.cc
index 4ff6602..868b9f4 100644
--- a/crypto/rand/urandom.cc
+++ b/crypto/rand/urandom.cc
@@ -28,14 +28,8 @@
 #include <fcntl.h>
 #include <stdio.h>
 #include <string.h>
-#include <unistd.h>
-
-#if defined(OPENSSL_LINUX)
-#if defined(BORINGSSL_FIPS)
-#include <linux/random.h>
-#include <sys/ioctl.h>
-#endif
 #include <sys/syscall.h>
+#include <unistd.h>
 
 #if defined(OPENSSL_ANDROID)
 #include <sys/system_properties.h>
@@ -57,7 +51,6 @@
 #if defined(OPENSSL_HAS_GETAUXVAL)
 #include <sys/auxv.h>
 #endif
-#endif  // OPENSSL_LINUX
 
 #include <openssl/mem.h>
 
@@ -248,14 +241,11 @@
     return 1;
   }
 
-#if defined(USE_NR_getrandom) || defined(FREEBSD_GETRANDOM)
+#if defined(USE_NR_getrandom)
   int getrandom_flags = 0;
   if (!block) {
     getrandom_flags |= GRND_NONBLOCK;
   }
-#endif
-
-#if defined(USE_NR_getrandom)
   if (seed) {
     getrandom_flags |= extra_getrandom_flags_for_seed;
   }