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: I04e4f984781e60feb355de7adf80c54300e0d1f5
diff --git a/Android.bp b/Android.bp
index b8a4f82..0e57c12 100644
--- a/Android.bp
+++ b/Android.bp
@@ -339,7 +339,7 @@
         linux_bionic: {
             enabled: true,
         },
-        linux: {
+        linux_glibc: {
             enabled: false,
         },
         darwin: {
@@ -360,7 +360,7 @@
         linux_bionic: {
             enabled: true,
         },
-        linux: {
+        linux_glibc: {
             enabled: false,
         },
         darwin: {