Add TARGET_PLATFORM_VERSION to lunch

lunch can now take combos in the form:
$TARGET_PRODUCT
$TARGET_PRODUCT-$TARGET_BUILD_VARIANT
$TARGET_PRODUCT-$TARGET_BUILD_VARIANT-$TARGET_PLATFORM_VERSION

If all 3 are not specified the unspecified ones will take the
default values provided by the build system (eng, and currently
OPR1).

In addition, error handling for invalid products, variants and
versions is moved to the build system.

Bug: 34972208
Test: build/make/tests/envsetup_tests.sh
Change-Id: Ib0aaa98633448ba9bd8df911704c9cb3a8ebbe85
diff --git a/buildspec.mk.default b/buildspec.mk.default
index a7ac7ec..b31578a 100644
--- a/buildspec.mk.default
+++ b/buildspec.mk.default
@@ -36,6 +36,12 @@
 #TARGET_BUILD_VARIANT:=eng
 endif
 
+# Choose a targeted release.  If you don't pick one, the default is the
+# soonest future release.
+ifndef TARGET_PLATFORM_RELEASE
+#TARGET_PLATFORM_RELEASE:=OPR1
+endif
+
 # Choose additional targets to always install, even when building
 # minimal targets like "make droid".  This takes simple target names
 # like "Browser" or "MyApp", the names used by LOCAL_MODULE or
@@ -105,4 +111,4 @@
 # variable will be changed.  After you have modified this file with the new
 # changes (see buildspec.mk.default), update this to the new value from
 # buildspec.mk.default.
-BUILD_ENV_SEQUENCE_NUMBER := 12
+BUILD_ENV_SEQUENCE_NUMBER := 13