Revert "O is API 26."

This reverts commit 06fc7e023b1db7f020171a1748d9743af5d21e6c.

Reason for revert:  b/37355569

Bug: 37480230
Bug: 37355569
Change-Id: I2eef4fb5369fa4e9d7a410461de63d4dd43dfc09
(cherry picked from commit 75feb8927ae20fc9ab3d0a256c1784aadacd3020)
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index 18ee6be..9340e54 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -104,14 +104,14 @@
   # When you increment the PLATFORM_SDK_VERSION please ensure you also
   # clear out the following text file of all older PLATFORM_VERSION's:
   # cts/tests/tests/os/assets/platform_versions.txt
-  PLATFORM_SDK_VERSION := 26
+  PLATFORM_SDK_VERSION := 25
 endif
 
 ifndef PLATFORM_JACK_MIN_SDK_VERSION
   # This is definition of the min SDK version given to Jack for the current
   # platform. For released version it should be the same as
   # PLATFORM_SDK_VERSION. During development, this number may be incremented
-  # before PLATFORM_SDK_VERSION if the platform starts to add new java
+  # before PLATFORM_SDK_VERSION if the plateform starts to add new java
   # language supports.
   PLATFORM_JACK_MIN_SDK_VERSION := o-b1
 endif