Added some build instructions.

zsnes/src/tools/compile.txt

@@ -0,0 +1,26 @@
+How to compile the tools.
+
+First build the utility files used by the tools.
+
+g++ -Wall -O3 -o fileutil.o -c fileutil.cpp
+g++ -Wall -O3 -o strutil.o -c strutil.cpp
+
+
+Minimize Whitespace:
+g++ -Wall -O3 -o minwhite.exe minwhite.cpp fileutil.o
+
+Extra EXTSYMs:
+g++ -Wall -O3 -o extraext.exe extraext.cpp fileutil.o strutil.o
+
+Section Tester:
+g++ -Wall -O3 -o sec-test.exe sec-test.cpp fileutil.o
+
+Source Counter:
+g++ -Wall -O3 -o srccount.exe srccount.cpp fileutil.o
+
+
+All the tools scan every compatible file they find from the directory
+they are in. It also scans all sub directories recursively.
+
+Extra EXTSYMs accepts command line arguments. You can specify filenames
+to put on the can't be opened ignore list.