[cmake] typo (#465)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 93d30a9..c2ae800 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -321,8 +321,8 @@
 try_compile(HB_HAVE_SOLARIS_ATOMIC_OPS
   ${PROJECT_BINARY_DIR}/try_compile_solaris_atomic_ops
   SOURCES ${PROJECT_BINARY_DIR}/try_compile_solaris_atomic_ops.c)
-if (HB_HB_HAVE_SOLARIS_ATOMIC_OPS)
-  add_definitions(-DHB_HAVE_SOLARIS_ATOMIC_OPS)
+if (HB_HAVE_SOLARIS_ATOMIC_OPS)
+  add_definitions(-DHAVE_SOLARIS_ATOMIC_OPS)
 endif ()
 ##