This commit is us getting out of our own way. We were specifying
-classpath twice, once in $(JAVAC) and once in java-build.mk. Only
the latter of these is active. This a problem for ANDROID_EXTRA_JARS
-- those JARs should be on the classpath and input to $(DX) -- and
JARs that should be on the classpath but *not* input to $(DX). This
commit removes the global flags to $(JAVAC) and adds
JAVA_{BOOT}CLASSPATH_JARS. This required some hijinkery moving
wildcards to moz.build files, but everything seems to work.
As well as clarifying some parts of the build, part 2 uses this work
to modify the classpath.
This patch also tries to verify that the tools are actually found
early in the configure process, rather than failing with difficult to
parse errors at the end of the build.
Since the Android developer tools are defined earlier in the build
process, we can remove a work-around needed for |make install|.
This incorporates follow-ups including: rename the debug key; check if
key alias exists rather than just testing for keystore existence; set
$(AIDL).
Renaming the debug key works around an un-confirmed JDK bug in
jarsigner, where '-debug' and 'debug' compare the same.
