chore: tidy up c binding build and docs (#5243)

Signed-off-by: tison <[email protected]>

Author: tisonkun

bindings/c/CMakeLists.txt

@@ -16,14 +16,15 @@
 # under the License.
 
 cmake_minimum_required(VERSION 3.22)
+cmake_policy(SET CMP0135 NEW)
+
 project(opendal-c)
 
 if (NOT CMAKE_BUILD_TYPE)
     set(CMAKE_BUILD_TYPE "Debug")
 endif()
 
 option(TEST_ENABLE_ASAN "Enable AddressSanitizer for tests" OFF)
-set(GOOGLETEST_VERSION 1.15.2)
 
 # force the compiler to support these standards
 set(CMAKE_C_STANDARD 11)
@@ -35,6 +36,8 @@ set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 # fetch google test via GitHub
 include(FetchContent)
+
+set(GOOGLETEST_VERSION 1.15.2)
 FetchContent_Declare(
   googletest
   URL https://github.com/google/googletest/archive/refs/tags/v${GOOGLETEST_VERSION}.zip

bindings/c/README.md

@@ -89,7 +89,7 @@ curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
 - To **build the library and header file**.
 
   ```sh
-  mkdir build && cd build
+  mkdir -p build && cd build
   cmake ..
   make
   ```