Check for __TRUSTY__ instead of TRUSTY.

Meant to do this shortly after filing the bug but forgot.

Bug: 377
Change-Id: Ic5a5c167a7b6745599e3a32c4792b66ebbb2dee0
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/49265
Reviewed-by: Adam Langley <agl@google.com>

include/openssl/base.h

diff --git a/include/openssl/base.h b/include/openssl/base.h
index dd6a146..223c0c5 100644
--- a/include/openssl/base.h
+++ b/include/openssl/base.h
@@ -145,7 +145,7 @@
 // Trusty isn't Linux but currently defines __linux__. As a workaround, we
 // exclude it here.
 // TODO(b/169780122): Remove this workaround once Trusty no longer defines it.
-#if defined(__linux__) && !defined(TRUSTY)
+#if defined(__linux__) && !defined(__TRUSTY__)
 #define OPENSSL_LINUX
 #endif
 
@@ -153,7 +153,7 @@
 #define OPENSSL_FUCHSIA
 #endif
 
-#if defined(TRUSTY)
+#if defined(__TRUSTY__)
 #define OPENSSL_TRUSTY
 #define OPENSSL_NO_THREADS_CORRUPT_MEMORY_AND_LEAK_SECRETS_IF_THREADED
 #endif