Fix OPENSSL_NO_ASM builds with the generated CMake build.

I inadverterntly broke this in
https://boringssl-review.googlesource.com/c/boringssl/+/56445

Bug: 542
Change-Id: I55dbf18314196d00f4ce19c3f59eabeccb17a8d7
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/56766
Auto-Submit: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>

util/generate_build_files.py

@@ -446,7 +446,9 @@ endif()
 
 add_definitions(-DBORINGSSL_IMPLEMENTATION)
 
-if(NOT OPENSSL_NO_ASM)
+if(OPENSSL_NO_ASM)
+  add_definitions(-DOPENSSL_NO_ASM)
+else()
   # On x86 and x86_64 Windows, we use the NASM output.
   if(WIN32 AND CMAKE_SYSTEM_PROCESSOR MATCHES "AMD64|x86_64|amd64|x86|i[3-6]86")
     enable_language(ASM_NASM)