build(aur): honor distro build flags in PKGBUILD

Export Arch-provided C/CGO flags and set Go build defaults for\nreproducible package builds. Use external linking so ldflags and\ntoolchain hardening are applied consistently.

Author: chpock

dist/aur/gen-commit-msg-git/PKGBUILD

@@ -32,6 +32,13 @@ pkgver() {
 build() {
     cd "gen-commit-msg"
     local tag commits hash build_version
+
+    export CGO_CPPFLAGS="${CPPFLAGS}"
+    export CGO_CFLAGS="${CFLAGS}"
+    export CGO_CXXFLAGS="${CXXFLAGS}"
+    export CGO_LDFLAGS="${LDFLAGS}"
+    export GOFLAGS="-buildmode=pie -trimpath -mod=readonly -modcacherw"
+
     tag=$(git describe --tags --abbrev=0 2>/dev/null || true)
     commits=$(git rev-list --count HEAD)
     hash=$(git rev-parse --short HEAD)
@@ -42,7 +49,7 @@ build() {
         build_version="0.0.0+${commits}.g${hash}"
     fi
 
-    go build -ldflags "-X main.version=${build_version}" -o gen-commit-msg ./cmd/gen-commit-msg
+    go build -ldflags "-linkmode=external -X main.version=${build_version}" -o gen-commit-msg ./cmd/gen-commit-msg
 }
 
 package() {

dist/aur/gen-commit-msg/PKGBUILD

@@ -16,7 +16,14 @@ sha256sums=('SHA256_PLACEHOLDER')
 
 build() {
     cd "$pkgname-$pkgver"
-    go build -ldflags "-X main.version=$pkgver" -o gen-commit-msg ./cmd/gen-commit-msg
+
+    export CGO_CPPFLAGS="${CPPFLAGS}"
+    export CGO_CFLAGS="${CFLAGS}"
+    export CGO_CXXFLAGS="${CXXFLAGS}"
+    export CGO_LDFLAGS="${LDFLAGS}"
+    export GOFLAGS="-buildmode=pie -trimpath -mod=readonly -modcacherw"
+
+    go build -ldflags "-linkmode=external -X main.version=$pkgver" -o gen-commit-msg ./cmd/gen-commit-msg
 }
 
 package() {