CI: fail build on compiler and bison warnings (#2398)

- installcheck.yaml: build with COPT=-Werror so compiler warnings fail CI
- Makefile: add -Werror to BISONFLAGS for cypher_gram.c so bison
  conflicts/warnings fail the build

Author: MuhammadTahaNaveed

.github/workflows/installcheck.yaml

@@ -48,7 +48,7 @@ jobs:
       - name: Build AGE
         id: build
         run: |
-          make PG_CONFIG=$HOME/pg18/bin/pg_config install -j$(nproc)
+          make PG_CONFIG=$HOME/pg18/bin/pg_config COPT=-Werror install -j$(nproc)
 
       - name: Pull and build pgvector
         id: pgvector

Makefile

@@ -221,7 +221,7 @@ src/include/parser/cypher_kwlist_d.h: src/include/parser/cypher_kwlist.h $(GEN_K
 
 src/include/parser/cypher_gram_def.h: src/backend/parser/cypher_gram.c
 
-src/backend/parser/cypher_gram.c: BISONFLAGS += --defines=src/include/parser/cypher_gram_def.h
+src/backend/parser/cypher_gram.c: BISONFLAGS += --defines=src/include/parser/cypher_gram_def.h -Werror
 
 src/backend/parser/cypher_parser.o: src/backend/parser/cypher_gram.c src/include/parser/cypher_gram_def.h
 src/backend/parser/cypher_parser.bc: src/backend/parser/cypher_gram.c src/include/parser/cypher_gram_def.h