Add target.linux_glibc and target.bionic

target.linux_glibc will apply to host builds with glibc, which is
identical to the current target.linux. In a future change, target.linux
will change to affect all targets using the Linux kernel (android,
linux_bionic, and linux_glibc).

target.bionic will apply to all OS variants using Bionic.

Bug: 31559095
Test: Add target.linux_glibc, target.bionic sections to an Android.bp, build
Test: m host
Change-Id: I677a67c22fba148fec264132311e355283f9d88d
diff --git a/android/androidmk.go b/android/androidmk.go
index 319f711..5ce486d 100644
--- a/android/androidmk.go
+++ b/android/androidmk.go
@@ -243,7 +243,11 @@
 	}
 
 	if host {
-		fmt.Fprintln(&data.preamble, "LOCAL_MODULE_HOST_OS :=", amod.Os().String())
+		makeOs := amod.Os().String()
+		if amod.Os() == Linux || amod.Os() == LinuxBionic {
+			makeOs = "linux"
+		}
+		fmt.Fprintln(&data.preamble, "LOCAL_MODULE_HOST_OS :=", makeOs)
 		fmt.Fprintln(&data.preamble, "LOCAL_IS_HOST_MODULE := true")
 	}