Fix: recovery module is disabled on 32-bit targets

Fixed a bug that recovery variant of a module is not created on 32-bit
targets. The bug was happening because the creation of the recovery
variant relied on DevicePrefer32BitExecutables() which returns false
for 32-bit only targets.

Now, recovery variant is checked against the primary architecture of the
device that is returned by DevicePrimaryArchType().

Test: m -j adbd.recovery on aosp_arm and aosp_arm64
adbd is built under recovery/root/system/bin and it is ELF32 and ELF64,
respectively for the targets.
Test: m -j libc.recovery on aosp_arm, aosp_arm64, aosp_sailfish
and the x86+arm target in mater. Only one libc.so is installed
under recovery/root/system/lib (or lib64).

Change-Id: I83a248d81f2c71dcfb0e9d887a75b71338f27b4d

android/config.go

@@ -576,6 +576,10 @@ func (c *config) DevicePrefer32BitExecutables() bool {
 	return Bool(c.productVariables.DevicePrefer32BitExecutables)
 }
 
+func (c *config) DevicePrimaryArchType() ArchType {
+	return c.Targets[Device][0].Arch.ArchType
+}
+
 func (c *config) SkipDeviceInstall() bool {
 	return c.EmbeddedInMake()
 }