update build.sh

build.sh

@@ -4,4 +4,4 @@
 # -DCMAKE_INSTALL_PREFIX=/home/xuqiang/633/spdlog/build/install \
 # -B build -S .
 
-cmake -B build -S . && cmake --build build
+cmake -B build -S . && cmake --build build -j$(nproc)