fix(main/termux-keyring): fix force rebuild which failed due to creat…

…ing the key symlink at path which already existed from previous build as `ln -f` flag was not passed

This all removes any keys left over from previous versions that do not exist in newer version.

```
./build-package.sh termux-keyring
./build-package.sh -f termux-keyring
ln: failed to create symbolic link '/data/data/com.termux/files/usr/etc/apt/trusted.gpg.d/2096779623.gpg': File exists
```

packages/termux-keyring/build.sh

@@ -3,6 +3,7 @@ TERMUX_PKG_DESCRIPTION="GPG public keys for the official Termux repositories"
 TERMUX_PKG_LICENSE="Apache-2.0"
 TERMUX_PKG_MAINTAINER="@termux"
 TERMUX_PKG_VERSION=3.12
+TERMUX_PKG_REVISION=1
 TERMUX_PKG_AUTO_UPDATE=false
 TERMUX_PKG_SKIP_SRC_EXTRACT=true
 TERMUX_PKG_PLATFORM_INDEPENDENT=true
@@ -11,6 +12,8 @@ TERMUX_PKG_ESSENTIAL=true
 termux_step_make_install() {
 	local GPG_SHARE_DIR="$TERMUX_PREFIX/share/termux-keyring"
 
+	# Delete all existing termux-keyring keys
+	rm -rf "$GPG_SHARE_DIR"
 	mkdir -p "$GPG_SHARE_DIR"
 
 	# Maintainer-specific keys.
@@ -27,13 +30,17 @@ termux_step_make_install() {
 	# Key for pacman package manager.
 	install -Dm600 "$TERMUX_PKG_BUILDER_DIR/termux-pacman.gpg" "$GPG_SHARE_DIR"
 
+	# Create symlinks under all GPG_DIRs to key files under GPG_SHARE_DIR
 	for GPG_DIR in "$TERMUX_PREFIX/etc/apt/trusted.gpg.d" "$TERMUX_PREFIX/share/pacman/keyrings"; do
 		mkdir -p "$GPG_DIR"
+		# Delete keys which have been removed in newer version and their symlink target does not exist
+		find "$GPG_DIR" -xtype l -printf 'Deleting removed key: %p\n' -delete
 		for GPG_FILE in "$GPG_SHARE_DIR"/*.gpg; do
 			if [[ "$GPG_DIR" == *"/apt/"* && "$GPG_FILE" == *"termux-pacman.gpg"* ]]; then
 				continue
 			fi
-			ln -s "$GPG_FILE" "$GPG_DIR/$(basename "$GPG_FILE")"
+			# Create or overwrite key symlink
+			ln -sf "$GPG_FILE" "$GPG_DIR/$(basename "$GPG_FILE")"
 		done
 		# Creation of trusted files
 		if [[ "$GPG_DIR" == *"/pacman/"* ]]; then