Prior to this change, when signing APKs, the build system invoked
'aapt dump badging' on each APK, to detect the value to pass into
signapk as --min-sdk-version. Now that signapk uses the apksig
library, it can auto-detect that value on its own, thus avoiding the
need to invoke 'aapt dump badging' and thus speeding up the build
process.
The semantics of signapk's --min-sdk-version flag is changed by this
commit from having the default value of 0 to having the default value
of "auto-detect from APK".
P.S. The get-package-min-sdk-version-int is not removed from
core/definitions.mk in this commnit, because this function is used in
another project's .mk file and thus that .mk file needs to be modified
first.
Test: rm -Rf out/ && make
Change-Id: I0972fcf0abbde9cbf6794e6c05c743c77c8a78f9
9b75e272b6