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: Ib273f63b51b87b54a211936bb167a9a4d668bd8e
Exempt-From-Owner-Approval: build system cleanup
diff --git a/tools/Android.bp b/tools/Android.bp
index e2999bf..6f2d1ac 100644
--- a/tools/Android.bp
+++ b/tools/Android.bp
@@ -2,7 +2,7 @@
     name: "libLLVM",
     host_supported: true,
     target: {
-        linux_x86_64: {
+        linux_glibc_x86_64: {
             srcs: ["linux/lib64/libLLVM.so"],
         },
         darwin_x86_64: {
@@ -21,7 +21,7 @@
     name: "libclang",
     host_supported: true,
     target: {
-        linux_x86_64: {
+        linux_glibc_x86_64: {
             srcs: ["linux/lib64/libclang.so"],
         },
         darwin_x86_64: {