configure: Turn optimization back on iff --enable-optimize

configure

@@ -645,6 +645,11 @@ esac
 # Adjust perf and debug options for debug mode
 if [ -n "$CFG_ENABLE_DEBUG" ]; then
     msg "debug mode enabled, setting performance options"
+    if [ -z "$CFG_ENABLE_OPTIMIZE_PROVIDED" ]; then
+        msg "optimization not explicitly enabled, disabling optimization"
+        CFG_DISABLE_OPTIMIZE=1
+        CFG_DISABLE_OPTIMIZE_CXX=1
+    fi
     CFG_ENABLE_LLVM_ASSERTIONS=1
     CFG_ENABLE_DEBUG_ASSERTIONS=1
     CFG_ENABLE_DEBUG_JEMALLOC=1