Add gdb prebuilts to the pdk.

Change-Id: Idc735d460a0a838d466dfca6483c0b4700071f4e
diff --git a/default.xml b/default.xml
index 7ffeb82..0a977da 100644
--- a/default.xml
+++ b/default.xml
@@ -597,8 +597,8 @@
   <project path="prebuilts/gcc/linux-x86/host/x86_64-w64-mingw32-4.8" name="platform/prebuilts/gcc/linux-x86/host/x86_64-w64-mingw32-4.8" groups="pdk-fs" clone-depth="1" />
   <project path="prebuilts/gcc/linux-x86/mips/mips64el-linux-android-4.9" name="platform/prebuilts/gcc/linux-x86/mips/mips64el-linux-android-4.9" groups="pdk,linux,mips" clone-depth="1" />
   <project path="prebuilts/gcc/linux-x86/x86/x86_64-linux-android-4.9" name="platform/prebuilts/gcc/linux-x86/x86/x86_64-linux-android-4.9" groups="pdk,linux,x86" clone-depth="1" />
-  <project path="prebuilts/gdb/darwin-x86" name="platform/prebuilts/gdb/darwin-x86" groups="darwin" clone-depth="1" />
-  <project path="prebuilts/gdb/linux-x86" name="platform/prebuilts/gdb/linux-x86" groups="linux" clone-depth="1" />
+  <project path="prebuilts/gdb/darwin-x86" name="platform/prebuilts/gdb/darwin-x86" groups="darwin,pdk" clone-depth="1" />
+  <project path="prebuilts/gdb/linux-x86" name="platform/prebuilts/gdb/linux-x86" groups="linux,pdk" clone-depth="1" />
   <project path="prebuilts/go/darwin-x86" name="platform/prebuilts/go/darwin-x86" groups="darwin,pdk,tradefed" clone-depth="1" />
   <project path="prebuilts/go/linux-x86" name="platform/prebuilts/go/linux-x86" groups="linux,pdk,tradefed" clone-depth="1" />
   <project path="prebuilts/gradle-plugin" name="platform/prebuilts/gradle-plugin" groups="pdk-cw-fs,pdk-fs" clone-depth="1" />