Print error of `import-sql` at the end of the output (#1237)

Because of the parallel processing of `import-sql` the error message is printed in the middle of the output. With this PR the error is displayed again at the end:
![grafik](https://user-images.githubusercontent.com/19800037/133897373-656ed3d0-e580-4f67-9290-0e83949d63d7.png)

Issue: https://github.com/openmaptiles/openmaptiles-tools/pull/370

```
awk '1{print; fflush()} $$0~".*ERROR" {txt=$$0} END{ if(txt){print "\n*** ERROR detected, aborting:"; print txt; exit(1)} }'
```
Explanation:
- `1{print; fflush()}` means if true then print output -> `1{}` same as `if(true){}`
- `$$0~".*ERROR" {txt=$$0}` get first argument `$$0` (line of output) and check if it contains (regex string) `ERROR`. If true save line to var `txt`: `{txt=$$0}`
- `END{ ... }` if last line of output is reached
- `if(txt){print "\n*** ERROR detected, aborting:"; print txt; exit(1)}` if error was found in a line / var `txt` is existing print it out

Makefile

@@ -420,7 +420,8 @@ endif
 .PHONY: import-sql
 import-sql: all start-db-nowait
 	$(DOCKER_COMPOSE) run $(DC_OPTS) openmaptiles-tools sh -c 'pgwait && import-sql' | \
-	  awk -v s=": WARNING:" '1{print; fflush()} $$0~s{print "\n*** WARNING detected, aborting"; exit(1)}'
+    	awk -v s=": WARNING:" '1{print; fflush()} $$0~s{print "\n*** WARNING detected, aborting"; exit(1)}' | \
+    	awk '1{print; fflush()} $$0~".*ERROR" {txt=$$0} END{ if(txt){print "\n*** ERROR detected, aborting:"; print txt; exit(1)} }'
 
 .PHONY: generate-tiles
 generate-tiles: all start-db