build: split TARGET_PREFER_32_BIT for apps and executables

Introduce two new flags, TARGET_PREFER_32_BIT_APPS and
TARGET_PREFER_32_BIT_EXECUTABLES that individually control
compilation of apps and executables.  If TARGET_PREFER_32_BIT is
set, the build system will automatically set both new flags.

Change-Id: Ibd2165e688675c2884d9e7ddf82d7dd6c28521f3
diff --git a/core/executable.mk b/core/executable.mk
index b67ac36..7a3e08e 100644
--- a/core/executable.mk
+++ b/core/executable.mk
@@ -19,9 +19,9 @@
 LOCAL_NO_2ND_ARCH_MODULE_SUFFIX := true
 endif
 
-# if TARGET_PREFER_32_BIT is set, try to build 32-bit first
+# if TARGET_PREFER_32_BIT_EXECUTABLES is set, try to build 32-bit first
 ifdef TARGET_2ND_ARCH
-ifeq ($(TARGET_PREFER_32_BIT),true)
+ifeq ($(TARGET_PREFER_32_BIT_EXECUTABLES),true)
 LOCAL_2ND_ARCH_VAR_PREFIX := $(TARGET_2ND_ARCH_VAR_PREFIX)
 else
 LOCAL_2ND_ARCH_VAR_PREFIX :=
@@ -45,7 +45,7 @@
 ifdef TARGET_2ND_ARCH
 
 # check if the non-preferred arch is the primary or secondary
-ifeq ($(TARGET_PREFER_32_BIT),true)
+ifeq ($(TARGET_PREFER_32_BIT_EXECUTABLES),true)
 LOCAL_2ND_ARCH_VAR_PREFIX :=
 else
 LOCAL_2ND_ARCH_VAR_PREFIX := $(TARGET_2ND_ARCH_VAR_PREFIX)