Use just built CMake for Static SDK (#401)

* [Static Linux SDK] Build CMake first and avoid using host CMake

* Fix the path for CMake source dir

Author: shahmishal

swift-ci/sdks/static-linux/scripts/build.sh

@@ -229,6 +229,15 @@ function run() {
     "$@"
 }
 
+header "Building CMake from source"
+
+quiet_pushd ${source_dir}/swift-project/cmake
+run ./bootstrap --no-qt-gui -- -DCMAKE_USE_OPENSSL=OFF
+run make -j$parallel_jobs
+run export PATH=${source_dir}/swift-project/cmake/bin:$PATH
+quiet_popd
+run cmake --version
+
 header "Patching Musl"
 
 echo -n "Patching Musl for locale support... "
@@ -642,6 +651,7 @@ EOF
         --musl-path=${build_dir}/sdk_root \
         --linux-static-arch=$arch \
         --install-destdir=$sdk_root \
+        --cmake=${source_dir}/swift-project/cmake/bin/cmake \
         --install-prefix=/usr \
         --swift-install-components="libexec;stdlib;sdk-overlay" \
         --extra-cmake-options="-DSWIFT_SHOULD_BUILD_EMBEDDED_STDLIB=NO -DLLVM_USE_LINKER=lld -DLLVM_NO_DEAD_STRIP=On" \