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: I56c84d206fb1e98cd7ea0d8fb875de0ebd87ea5e
Exempt-From-Owner-Approval: build system cleanup
diff --git a/linker/Android.bp b/linker/Android.bp
index 9125fd6..2a581ea 100644
--- a/linker/Android.bp
+++ b/linker/Android.bp
@@ -26,7 +26,7 @@
     device_supported: false,
     target: {
         linux_bionic: { enabled: true },
-        linux: { enabled: false },
+        linux_glibc: { enabled: false },
         darwin: { enabled: false },
     },