Increase AdbClient read timeout

The previous value was not sufficient for Pixel 2 phones. One would have
hoped that the newer phones are faster, but that does not seem to be the
case here.

llvm-svn: 316993
diff --git a/lldb/source/Plugins/Platform/Android/AdbClient.cpp b/lldb/source/Plugins/Platform/Android/AdbClient.cpp
index d3bcee6..6e15eb2 100644
--- a/lldb/source/Plugins/Platform/Android/AdbClient.cpp
+++ b/lldb/source/Plugins/Platform/Android/AdbClient.cpp
@@ -46,7 +46,7 @@
 
 namespace {
 
-const seconds kReadTimeout(12);
+const seconds kReadTimeout(20);
 const char *kOKAY = "OKAY";
 const char *kFAIL = "FAIL";
 const char *kDATA = "DATA";