Support 'tapas help' for more-detailed tapas help

Bug: 64844028
Test: tapas help
Change-Id: I5629ca781e8cacfa6bb09828acf4160bbca3c3a5

envsetup.sh

diff --git a/envsetup.sh b/envsetup.sh
index a8bef92..ec100b1 100644
--- a/envsetup.sh
+++ b/envsetup.sh
@@ -644,11 +644,17 @@
 # Run tapas with one or more app names (from LOCAL_PACKAGE_NAME)
 function tapas()
 {
+    local showHelp="$(echo $* | xargs -n 1 echo | \grep -E '^(help)$' | xargs)"
     local arch="$(echo $* | xargs -n 1 echo | \grep -E '^(arm|x86|mips|armv5|arm64|x86_64|mips64)$' | xargs)"
     local variant="$(echo $* | xargs -n 1 echo | \grep -E '^(user|userdebug|eng)$' | xargs)"
     local density="$(echo $* | xargs -n 1 echo | \grep -E '^(ldpi|mdpi|tvdpi|hdpi|xhdpi|xxhdpi|xxxhdpi|alldpi)$' | xargs)"
     local apps="$(echo $* | xargs -n 1 echo | \grep -E -v '^(user|userdebug|eng|arm|x86|mips|armv5|arm64|x86_64|mips64|ldpi|mdpi|tvdpi|hdpi|xhdpi|xxhdpi|xxxhdpi|alldpi)$' | xargs)"
 
+    if [ "$showHelp" != "" ]; then
+      $(gettop)/build/make/tapasHelp.sh
+      return
+    fi
+
     if [ $(echo $arch | wc -w) -gt 1 ]; then
         echo "tapas: Error: Multiple build archs supplied: $arch"
         return