init: logd: Allow Developer settings to adjust logd size

- AID_SYSTEM can set persist.logd.size
- AID_SYSTEM can issue command to /dev/socket/logd to
  change the runtime global log sizes.
- Add support for ro.logd.size.* as populated by BoardConfig.mk
- Limit size to maximum ~3% of physical memory.

Bug: 14563261
Bug: 14627052
Change-Id: I606420db2e9d9d032296e71149e4a5b20cbd1137
diff --git a/init/property_service.c b/init/property_service.c
index 7e8d79a..4bcf883 100644
--- a/init/property_service.c
+++ b/init/property_service.c
@@ -90,6 +90,7 @@
     { "log.",             AID_SHELL,    0 },
     { "service.adb.root", AID_SHELL,    0 },
     { "service.adb.tcp.port", AID_SHELL,    0 },
+    { "persist.logd.size",AID_SYSTEM,   0 },
     { "persist.sys.",     AID_SYSTEM,   0 },
     { "persist.service.", AID_SYSTEM,   0 },
     { "persist.security.", AID_SYSTEM,   0 },