Use mold linker for faster compilation

.cargo/config.toml

@@ -0,0 +1,6 @@
+[target.x86_64-unknown-linux-gnu]
+linker = "clang"
+rustflags = [
+    "-C", "link-arg=-fuse-ld=mold",
+]
+

.ci/woodpecker/check.yml

@@ -9,6 +9,7 @@ pipeline:
       event: [push, pull_request]
     image: rust:1.59.0-slim
     commands:
+      - rm -r .cargo
       - apt-get -qq update && apt-get -yqq install pkg-config libssl-dev build-essential
       - cargo install sqlx-cli --features sqlite
       - cd quickpeep && bash dev_db.sh && cd ..

.ci/woodpecker/release.yml

@@ -17,6 +17,7 @@ pipeline:
 
     image: "rust:1.59.0"
     commands:
+      - rm -r .cargo
       - apt-get -qq update && apt-get -yqq install pkg-config libssl-dev build-essential
       - cargo install sqlx-cli --features sqlite
       - "qualsuff=`echo -$WOODPECKER_TAG-$WOODPECKER_ARCH | sed s%/%-%`"