Rename target.linux[_x86[_64]] to target.linux_glibc[_x86[_64]]

In the future, target.linux will apply to all targets running a linux kernel
(android, linux_glibc, linux_bionic). So move all current users to the specific
linux_glibc.

There will be another cleanup pass later that will move some instances back to
target.linux if the properties should be shared with target.android and
target.linux_bionic, but target.linux needs to be removed first.

Test: out/soong/build.ninja identical before/after
Change-Id: Ie56501a04e2e757391b855ece4c818c7a3d4cf5a
Exempt-From-Owner-Approval: build system cleanup
diff --git a/Android.bp b/Android.bp
index 6b71b62..b79999f 100644
--- a/Android.bp
+++ b/Android.bp
@@ -39,7 +39,7 @@
         android: {
             srcs: ["AsynchronousCloseMonitor.cpp"],
         },
-        linux: {
+        linux_glibc: {
             srcs: ["AsynchronousCloseMonitor.cpp"],
         },
     },