fix(common): check before using tput with a fallback for colors

The latest release of devtools has included some pretty printing
capabilities and fancy terminal stuff with the spinner and so on.

It seems like the existing safeguards to disable this for incapable
terminals were not enough though, therefore we saw two types of errors:

- offload-build:
  ```
  ==> Building in chroot for [extra] (x86_64)...
  tput: unknown terminal "unknown"
  tput: unknown terminal "unknown"
  tput: unknown terminal "unknown"
  ```
- repro builders:
  ```
  ==> Successfully switched <package> to version <version>
  tput: No value for $TERM and no -T specified
  ERROR: Failed checkout <package>
  ```

The recently included fail option made this error populate to the
command level and therefore increased its impact from a not so nice
logging message to a more severe problem which made the command abort.

We fix this by checking if tput is supported or else use the raw escape
sequences instead of tput commands.

Fixes: fedfc80 ("feat(term): add terminal utils to handle a dynamic spinner")
Fixes: 66e83c9 ("feat(version): pretty print and group together version check results")
Fixes: d0dc0e1 ("feat(search): add optional plain output formatting")
Signed-off-by: Christian Heusel <christian@heusel.eu>

src/lib/common.sh

@@ -34,9 +34,15 @@ export AUR_URL_SSH=aur@aur.archlinux.org
 # check if messages are to be printed using color
 if [[ -t 2 && "$TERM" != dumb ]] || [[ ${DEVTOOLS_COLOR} == always ]]; then
 	colorize
-	PURPLE="$(tput setaf 5)"
-	DARK_GREEN="$(tput setaf 2)"
-	UNDERLINE="$(tput smul)"
+	if tput setaf 0 &>/dev/null; then
+		PURPLE="$(tput setaf 5)"
+		DARK_GREEN="$(tput setaf 2)"
+		UNDERLINE="$(tput smul)"
+	else
+		PURPLE="\e[35m"
+		DARK_GREEN="\e[32m"
+		UNDERLINE="\e[4m"
+	fi
 else
 	# shellcheck disable=2034
 	declare -gr ALL_OFF='' BOLD='' BLUE='' GREEN='' RED='' YELLOW='' PURPLE='' DARK_GREEN='' UNDERLINE=''
@@ -108,7 +114,9 @@ cleanup() {
 	if [[ -n ${WORKDIR:-} ]] && $_setup_workdir; then
 		rm -rf "$WORKDIR"
 	fi
-	tput cnorm >&2
+	if tput setaf 0 &>/dev/null; then
+		tput cnorm >&2
+	fi
 	exit "${1:-0}"
 }