Make keymaster optional.

Keymaster is now optional because KeyMint can be used instead.  This
CL makes this change retroactively back to compatibility matrix v3,
per discussion with the Treble team.

Test: Replace Keymaster with KeyMint & build
Change-Id: Id26d5bac326c494e1810516582fdd56a42c04e0d
diff --git a/compatibility_matrices/compatibility_matrix.3.xml b/compatibility_matrices/compatibility_matrix.3.xml
index 608890b..a75ed25 100644
--- a/compatibility_matrices/compatibility_matrix.3.xml
+++ b/compatibility_matrices/compatibility_matrix.3.xml
@@ -223,7 +223,7 @@
             <instance>default</instance>
         </interface>
     </hal>
-    <hal format="hidl" optional="false">
+    <hal format="hidl" optional="true">
         <name>android.hardware.keymaster</name>
         <version>3.0</version>
         <version>4.0</version>
diff --git a/compatibility_matrices/compatibility_matrix.4.xml b/compatibility_matrices/compatibility_matrix.4.xml
index e5e012c..3b8ee21 100644
--- a/compatibility_matrices/compatibility_matrix.4.xml
+++ b/compatibility_matrices/compatibility_matrix.4.xml
@@ -245,7 +245,7 @@
             <instance>default</instance>
         </interface>
     </hal>
-    <hal format="hidl" optional="false">
+    <hal format="hidl" optional="true">
         <name>android.hardware.keymaster</name>
         <version>3.0</version>
         <version>4.0</version>
diff --git a/compatibility_matrices/compatibility_matrix.5.xml b/compatibility_matrices/compatibility_matrix.5.xml
index 8e175f0..0fb21a7 100644
--- a/compatibility_matrices/compatibility_matrix.5.xml
+++ b/compatibility_matrices/compatibility_matrix.5.xml
@@ -284,7 +284,7 @@
             <instance>default</instance>
         </interface>
     </hal>
-    <hal format="hidl" optional="false">
+    <hal format="hidl" optional="true">
         <name>android.hardware.keymaster</name>
         <version>3.0</version>
         <version>4.0-1</version>
diff --git a/compatibility_matrices/compatibility_matrix.current.xml b/compatibility_matrices/compatibility_matrix.current.xml
index 30af25f..039ea84 100644
--- a/compatibility_matrices/compatibility_matrix.current.xml
+++ b/compatibility_matrices/compatibility_matrix.current.xml
@@ -297,7 +297,7 @@
             <instance>default</instance>
         </interface>
     </hal>
-    <hal format="hidl" optional="false">
+    <hal format="hidl" optional="true">
         <name>android.hardware.keymaster</name>
         <version>3.0</version>
         <version>4.0-1</version>