kbuild: Rename HOSTCFLAGS to KBUILD_HOSTCFLAGS

In preparation for enabling command line CFLAGS, re-name HOSTCFLAGS to
KBUILD_HOSTCFLAGS as the internal use only flags. This should not have
any visible effects.

Signed-off-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/Makefile b/Makefile
index a89d8a0..c364e11 100644
--- a/Makefile
+++ b/Makefile
@@ -359,7 +359,7 @@
 
 HOSTCC       = gcc
 HOSTCXX      = g++
-HOSTCFLAGS   := -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 \
+KBUILD_HOSTCFLAGS   := -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 \
 		-fomit-frame-pointer -std=gnu89 $(HOST_LFS_CFLAGS)
 HOSTCXXFLAGS := -O2 $(HOST_LFS_CFLAGS)
 HOSTLDFLAGS  := $(HOST_LFS_LDFLAGS)
@@ -429,7 +429,7 @@
 LDFLAGS :=
 GCC_PLUGINS_CFLAGS :=
 
-export ARCH SRCARCH CONFIG_SHELL HOSTCC HOSTCFLAGS CROSS_COMPILE AS LD CC
+export ARCH SRCARCH CONFIG_SHELL HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE AS LD CC
 export CPP AR NM STRIP OBJCOPY OBJDUMP HOSTLDFLAGS HOST_LOADLIBES
 export MAKE LEX YACC AWK GENKSYMS INSTALLKERNEL PERL PYTHON PYTHON2 PYTHON3 UTS_MACHINE
 export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS