add a "most" target, and make it the default

split out of https://codereview.appspot.com/6651064/ ('gyp: generate "everything" and "most" targets instead of "all"')
tests: "make most" now works, "make" now calls "make most"
Review URL: https://codereview.appspot.com/6740045

git-svn-id: http://skia.googlecode.com/svn/trunk@5999 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/Makefile b/Makefile
index 20dc224..e4ec9ef 100644
--- a/Makefile
+++ b/Makefile
@@ -32,6 +32,7 @@
 ALL_TARGETS := skia_base_libs \
                bench \
                gm \
+               most \
                SampleApp \
                tests \
                tools
@@ -42,7 +43,7 @@
 
 # Default target.  This must be listed before all other targets.
 .PHONY: default
-default: $(ALL_TARGETS)
+default: most
 
 # As noted in http://code.google.com/p/skia/issues/detail?id=330 , building
 # multiple targets in parallel was failing.  The special .NOTPARALLEL target