Remove ext/json parser files generated by bison

The parser files for ext/json are generated by bison from the *.y file.
Parser files in Zend and sapi/phpdbg already follow such approach of
these files being ignored from tracking in the Git repository and they
are shipped via the release packages later on. This way the end users
still don't need to have bison dependency installed to install PHP.

The genfiles script was refactored to generate the ext/json parser and
lexer files.

.gitignore

@@ -156,6 +156,8 @@ php
 # ------------------------------------------------------------------------------
 # PHP parser files generated by bison during the build process
 # ------------------------------------------------------------------------------
+/ext/json/json_parser.tab.h
+/ext/json/json_parser.tab.c
 /sapi/phpdbg/phpdbg_parser.c
 /sapi/phpdbg/phpdbg_parser.h
 /sapi/phpdbg/phpdbg_parser.output

ext/json/Makefile.frag

@@ -1,5 +1,5 @@
 $(srcdir)/json_scanner.c: $(srcdir)/json_scanner.re
-	$(RE2C) $(RE2C_FLAGS) -t $(srcdir)/php_json_scanner_defs.h --no-generation-date -bci -o $@ $(srcdir)/json_scanner.re
+	@$(RE2C) $(RE2C_FLAGS) -t $(srcdir)/php_json_scanner_defs.h --no-generation-date -bci -o $@ $(srcdir)/json_scanner.re
 
 $(srcdir)/json_parser.tab.c: $(srcdir)/json_parser.y
-	$(YACC) --defines -l $(srcdir)/json_parser.y -o $@
+	@$(YACC) --defines -l $(srcdir)/json_parser.y -o $@