For emulator builds preopt system apps even if doing eng build

Following change disabled preopt for system apps when doing eng build:
    4df565786a5a8cbd841556241c7ecb0c9db286e6

    Build: Only preopt boot images in eng builds

    As a middle way between full preopt/high performance/long builds,
    and no preopt/low performance/fast turnaround, preopt only the
    boot image in eng builds.

    I4a2692f3ce84823cd40c6b7d672fd73257739ef8

This works well for devices, but first boot on emulator takes 10+mins.
Bypass the change by forcing preopt inside the BoardConfig.

Change-Id: I58d100cd65d2a09b644a90d91261102aab31fcbb
diff --git a/target/board/generic/BoardConfig.mk b/target/board/generic/BoardConfig.mk
index 325b0ce..b471f9a 100644
--- a/target/board/generic/BoardConfig.mk
+++ b/target/board/generic/BoardConfig.mk
@@ -35,6 +35,7 @@
 ifeq ($(HOST_OS),linux)
   ifeq ($(WITH_DEXPREOPT),)
     WITH_DEXPREOPT := true
+    WITH_DEXPREOPT_BOOT_IMG_ONLY := false
   endif
 endif
 
diff --git a/target/board/generic_arm64/BoardConfig.mk b/target/board/generic_arm64/BoardConfig.mk
index 02d0a6f..34fffed 100644
--- a/target/board/generic_arm64/BoardConfig.mk
+++ b/target/board/generic_arm64/BoardConfig.mk
@@ -65,6 +65,7 @@
 ifeq ($(HOST_OS),linux)
   ifeq ($(WITH_DEXPREOPT),)
     WITH_DEXPREOPT := true
+    WITH_DEXPREOPT_BOOT_IMG_ONLY := false
   endif
 endif
 
diff --git a/target/board/generic_mips/BoardConfig.mk b/target/board/generic_mips/BoardConfig.mk
index 1152105..b68d88b 100644
--- a/target/board/generic_mips/BoardConfig.mk
+++ b/target/board/generic_mips/BoardConfig.mk
@@ -42,6 +42,7 @@
 ifeq ($(HOST_OS),linux)
   ifeq ($(WITH_DEXPREOPT),)
     WITH_DEXPREOPT := true
+    WITH_DEXPREOPT_BOOT_IMG_ONLY := false
   endif
 endif
 
diff --git a/target/board/generic_mips64/BoardConfig.mk b/target/board/generic_mips64/BoardConfig.mk
index ed9c9b3..44e6287 100644
--- a/target/board/generic_mips64/BoardConfig.mk
+++ b/target/board/generic_mips64/BoardConfig.mk
@@ -57,6 +57,7 @@
 ifeq ($(HOST_OS),linux)
   ifeq ($(WITH_DEXPREOPT),)
     WITH_DEXPREOPT := true
+    WITH_DEXPREOPT_BOOT_IMG_ONLY := false
   endif
 endif
 
diff --git a/target/board/generic_x86/BoardConfig.mk b/target/board/generic_x86/BoardConfig.mk
index 50ecb98..f8ac496 100644
--- a/target/board/generic_x86/BoardConfig.mk
+++ b/target/board/generic_x86/BoardConfig.mk
@@ -22,6 +22,7 @@
 # of an SDK AVD. Note that this operation only works on Linux for now
 ifeq ($(HOST_OS),linux)
 WITH_DEXPREOPT ?= true
+WITH_DEXPREOPT_BOOT_IMG_ONLY ?= false
 endif
 
 # Build OpenGLES emulation host and guest libraries
diff --git a/target/board/generic_x86_64/BoardConfig.mk b/target/board/generic_x86_64/BoardConfig.mk
index 6958ba5..bd831f8 100755
--- a/target/board/generic_x86_64/BoardConfig.mk
+++ b/target/board/generic_x86_64/BoardConfig.mk
@@ -28,6 +28,7 @@
 # of an SDK AVD. Note that this operation only works on Linux for now
 ifeq ($(HOST_OS),linux)
 WITH_DEXPREOPT ?= true
+WITH_DEXPREOPT_BOOT_IMG_ONLY ?= false
 endif
 
 # Build OpenGLES emulation host and guest libraries
diff --git a/target/board/generic_x86_arm/BoardConfig.mk b/target/board/generic_x86_arm/BoardConfig.mk
index 6e2573e..75207fc 100644
--- a/target/board/generic_x86_arm/BoardConfig.mk
+++ b/target/board/generic_x86_arm/BoardConfig.mk
@@ -39,6 +39,7 @@
 ifeq ($(HOST_OS),linux)
   ifeq ($(WITH_DEXPREOPT),)
     WITH_DEXPREOPT := true
+    WITH_DEXPREOPT_BOOT_IMG_ONLY := false
   endif
 endif