Move the build in a volume to be reused between steps

Signed-off-by: Kevin Ottens <kevin.ottens@nextcloud.com>

.drone.yml

@@ -4,18 +4,25 @@ name: qt-5.12
 steps:
 - name: build and test
   image: nextcloudci/client-5.12:client-5.12-10
+  volumes:
+    - name: build
+      path: /drone/build
   commands:
     # Build client
     - /bin/bash -c "
       export CC=gcc-10 &&
       export CXX=g++-10 &&
-      mkdir build &&
-      cd build &&
-      cmake -D NO_SHIBBOLETH=1 -DBUILD_UPDATER=ON -DCMAKE_BUILD_TYPE=Debug -DUNIT_TESTING=1 -DSANITIZE_ADDRESS=ON ../ &&
+      cd /drone/build &&
+      cmake -DNO_SHIBBOLETH=1 -DBUILD_UPDATER=ON -DCMAKE_BUILD_TYPE=Debug -DUNIT_TESTING=1 -DSANITIZE_ADDRESS=ON ../src &&
       make -j$(nproc) &&
       useradd -m -s /bin/bash test &&
       chown -R test:test . &&
       su -c 'ASAN_OPTIONS=detect_leaks=0 ctest --output-on-failure' test"
+
+volumes:
+- name: build
+  temp: {}
+
 trigger:
   branch:
     - master
@@ -30,20 +37,27 @@ name: qt-5.12-clang
 steps:
 - name: build and test
   image: nextcloudci/client-5.12:client-5.12-10
+  volumes:
+    - name: build
+      path: /drone/build
   commands:
     # Build client
     - /bin/bash -c "
       export CC=clang-10 &&
       export CXX=clang++-10 &&
-      mkdir build &&
-      cd build &&
-      cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -DNO_SHIBBOLETH=1 -DBUILD_UPDATER=ON -DCMAKE_BUILD_TYPE=Debug -DUNIT_TESTING=1 -DSANITIZE_ADDRESS=ON ../ &&
+      cd /drone/build &&
+      cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -DNO_SHIBBOLETH=1 -DBUILD_UPDATER=ON -DCMAKE_BUILD_TYPE=Debug -DUNIT_TESTING=1 -DSANITIZE_ADDRESS=ON ../src &&
       make -j$(nproc) &&
       useradd -m -s /bin/bash test &&
       chown -R test:test . &&
       su -c 'ASAN_OPTIONS=detect_leaks=0 ctest --output-on-failure' test"
     # Static analysis with clang-tidy
-    - "! run-clang-tidy-10 -p build -quiet | grep -A 5 ': error:'"
+    - "! run-clang-tidy-10 -p /drone/build -quiet | grep -A 5 ': error:'"
+
+volumes:
+- name: build
+  temp: {}
+
 trigger:
   branch:
     - master