Fix typo in setting up CMAKE_CXX_FLAGS

This will likely unbreak the OSS-Fuzz build. Whoops.

Bug: 470286193
Change-Id: I513ac8a566c539b59f97b153b8339e40199d398d
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/87067
Auto-Submit: David Benjamin <davidben@google.com>
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: Adam Langley <agl@google.com>

CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5745933..6bddfa2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -129,7 +129,7 @@
     set(C_CXX_FLAGS "${C_CXX_FLAGS} -fno-common -fvisibility=hidden")
   endif()
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${C_CXX_FLAGS}")
-  set(CMAKE_CXX_FLAGS "${CMAKE_C_FLAGS} ${C_CXX_FLAGS}")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${C_CXX_FLAGS}")
 elseif(MSVC)
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -utf-8")
   # Without /Zc:__cplusplus, MSVC does not define the right value for