cmake: correct the definition of USE_SYS_DYN_MEM with new macro name CAPSTONE_USE_SYS_DYN_MEM
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4d451d1..ef7fb83 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -15,7 +15,7 @@
 option(X86_SUPPORT "x86 support" ON)
 
 if (USE_DEFAULT_ALLOC)
-    add_definitions(-DUSE_SYS_DYN_MEM)
+    add_definitions(-DCAPSTONE_USE_SYS_DYN_MEM)
 endif ()
 
 set(SOURCES