kernel: Switch back to host openssl entirely

* OpenSSL cannot be statically linked because of
  getaddrinfo and gethostbyname calls.
* Also according to soong it's whitelisted:

Change-Id: I5ae17aa71b4b4d42b41151d5360356522947c44c
diff --git a/config/BoardConfigKernel.mk b/config/BoardConfigKernel.mk
index 9a5af6e..97e6e86 100644
--- a/config/BoardConfigKernel.mk
+++ b/config/BoardConfigKernel.mk
@@ -1,4 +1,4 @@
-# Copyright (C) 2018 The LineageOS Project
+# Copyright (C) 2018-2019 The LineageOS Project
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -116,13 +116,10 @@
 endif
 
 ifeq ($(HOST_OS),darwin)
-  KERNEL_MAKE_FLAGS += C_INCLUDE_PATH=$(BUILD_TOP)/external/elfutils/libelf:$(BUILD_TOP)/prebuilts/openssl/$(HOST_OS)-x86/1.1.1/include
+  KERNEL_MAKE_FLAGS += HOSTCFLAGS="-I$(BUILD_TOP)/external/elfutils/libelf -I/usr/local/opt/openssl/include -L/usr/local/opt/openssl/lib"
 else
-  KERNEL_MAKE_FLAGS += C_INCLUDE_PATH=$(BUILD_TOP)/prebuilts/openssl/$(HOST_OS)-x86/1.1.1/include
+  KERNEL_MAKE_FLAGS += HOSTCFLAGS="-I/usr/include -I/usr/include/x86_64-linux-gnu -L/usr/lib/x86_64-linux-gnu -L/usr/lib64"
 endif
-KERNEL_MAKE_FLAGS += LIBRARY_PATH=$(BUILD_TOP)/prebuilts/openssl/$(HOST_OS)-x86/1.1.1/lib
-KERNEL_MAKE_FLAGS += HOSTCFLAGS="-L $(BUILD_TOP)/prebuilts/openssl/$(HOST_OS)-x86/1.1.1/lib"
-KERNEL_MAKE_FLAGS += HOSTLDFLAGS="-L $(BUILD_TOP)/prebuilts/openssl/$(HOST_OS)-x86/1.1.1/lib"
 
 ifneq ($(TARGET_KERNEL_ADDITIONAL_FLAGS),)
   KERNEL_MAKE_FLAGS += $(TARGET_KERNEL_ADDITIONAL_FLAGS)