Improvements to makefile

Summary: Various improvements to the XHPAST `Makefile`.

Test Plan:
```
> make -C support/xhpast cleanall parser scanner xhpast
make: Entering directory '/home/joshua/workspace/github.com/phacility/libphutil/support/xhpast'
rm --force xhpast parser.yacc.output libxhpast.a *.o
rm --force scanner.lex.hpp scanner.lex.cpp parser.yacc.hpp parser.yacc.cpp
rm --force node_names.hpp parser_nodes.php
bison --verbose -Wall --defines=parser.yacc.hpp --output=parser.yacc.cpp parser.y
flex -CFr --header-file=scanner.lex.hpp --outfile=scanner.lex.cpp scanner.l
php -f generate_nodes.php
Wrote C++ definition.
Wrote PHP definition.
g++ -c -fPIC -Wall -O3 -minline-all-stringops -o scanner.lex.o scanner.lex.cpp
g++ -c -fPIC -Wall -O3 -minline-all-stringops -o parser.yacc.o parser.yacc.cpp
ar -crs libxhpast.a scanner.lex.o parser.yacc.o
g++ -fPIC -Wall -O3 -minline-all-stringops -o xhpast xhpast.cpp libxhpast.a
make: Leaving directory '/home/joshua/workspace/github.com/phacility/libphutil/support/xhpast'
```

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D13978

Author: joshuaspence

.gitignore

@@ -11,6 +11,7 @@
 /support/xhpast/parser.yacc.output
 /support/xhpast/node_names.hpp
 /support/xhpast/xhpast
+/support/xhpast/xhpast.exe
 /src/parser/xhpast/bin/xhpast
 
 ## NOTE: Don't .gitignore these files! Even though they're build artifacts, we
@@ -23,9 +24,6 @@
 # This is an OS X build artifact.
 /support/xhpast/xhpast.dSYM
 
-# This is a Windows build artifact.
-/support/xhpast/xhpast.exe
-
 # libphutil
 /src/.phutil_module_cache
 /support/phutiltestlib/.phutil_module_cache

support/xhpast/Makefile

@@ -1,4 +1,4 @@
-BISONFLAGS = --verbose -d -Wall
+BISONFLAGS = --verbose -Wall
 CPPFLAGS   = -fPIC -Wall
 FLEXFLAGS  = -CFr
 
@@ -24,47 +24,45 @@ endif
 
 ROOT = ../../src/parser/xhpast
 
+.PHONY: all
 all: xhpast
 
 clean:
-	-rm xhpast parser.yacc.output libxhpast.a *.o 2>/dev/null
+	rm --force xhpast parser.yacc.output libxhpast.a *.o
 
 cleanall: clean
-	-rm scanner.lex.cpp scanner.lex.hpp parser.yacc.cpp parser.yacc.hpp
+	rm --force scanner.lex.hpp scanner.lex.cpp parser.yacc.hpp parser.yacc.cpp
+	rm --force node_names.hpp parser_nodes.php
 
+.PHONY: install
 install: xhpast
 	cp xhpast $(ROOT)/bin/xhpast
 
-scanner: scanner.l
-	flex $(FLEXFLAGS) --header-file=scanner.lex.hpp --outfile=scanner.lex.cpp $<
-	echo '/* @gen''er''ated */' >> scanner.lex.cpp
-	echo '/* @gen''er''ated */' >> scanner.lex.hpp
+.PHONY: parser scanner
+parser: parser.yacc.hpp parser.yacc.cpp
+scanner: scanner.lex.hpp scanner.lex.cpp
 
-parser: parser.y
-	bison $(BISONFLAGS) --output=parser.yacc.cpp $<
-	echo '/* @gen''er''ated */' >> parser.yacc.cpp
-	echo '/* @gen''er''ated */' >> parser.yacc.hpp
+%.lex.hpp %.lex.cpp: %.l
+	flex $(FLEXFLAGS) --header-file=$*.lex.hpp --outfile=$*.lex.cpp $<
+	@echo '/* @gen''er''ated */' >> $*.lex.hpp
+	@echo '/* @gen''er''ated */' >> $*.lex.cpp
 
-node_names.hpp: generate_nodes.php
-	php -f generate_nodes.php
-	cp parser_nodes.php $(ROOT)/
+%.yacc.hpp %.yacc.cpp: %.y
+	bison $(BISONFLAGS) --defines=$*.yacc.hpp --output=$*.yacc.cpp $<
+	@echo '/* @gen''er''ated */' >> $*.yacc.hpp
+	@echo '/* @gen''er''ated */' >> $*.yacc.cpp
 
 %.o: %.cpp
 	$(CXX) -c $(CPPFLAGS) -o $@ $<
 
-needparserscanner:
-	 @([ -e parser.yacc.hpp ] && [ -e parser.yacc.cpp ] && \
-	   [ -e scanner.lex.hpp ] && [ -e scanner.lex.cpp ]) \
-		|| (echo "Run 'make parser scanner' first.'" && exit 1)
+node_names.hpp parser_nodes.php: generate_nodes.php
+	php -f $<
 
-parser.yacc.o: needparserscanner scanner.lex.hpp
-
-scanner.lex.o: needparserscanner parser.yacc.hpp node_names.hpp scanner.lex.hpp
+parser.yacc.o: scanner.lex.hpp
+scanner.lex.o: parser.yacc.hpp node_names.hpp scanner.lex.hpp
 
 libxhpast.a: scanner.lex.o parser.yacc.o
 	$(AR) -crs $@ $^
 
 xhpast: xhpast.cpp libxhpast.a
 	$(CXX) $(CPPFLAGS) -o $@ $^
-
-.PHONY: all clean