kbuild: Use HOST*FLAGS options from the command line

Now that we have the rename in place, reuse the HOST*FLAGS options as
something that can be set from the command line and included with the
rest of the flags.
Signed-off-by: NLaura Abbott <labbott@redhat.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Documentation/kbuild/kbuild.txt

@@ -50,6 +50,22 @@ LDFLAGS_MODULE
 --------------------------------------------------
 Additional options used for $(LD) when linking modules.
 
+HOSTCFLAGS
+--------------------------------------------------
+Additional flags to be passed to $(HOSTCC) when building host programs.
+
+HOSTCXXFLAGS
+--------------------------------------------------
+Additional flags to be passed to $(HOSTCXX) when building host programs.
+
+HOSTLDFLAGS
+--------------------------------------------------
+Additional flags to be passed when linking host programs.
+
+HOSTLDLIBS
+--------------------------------------------------
+Additional libraries to link against when building host programs.
+
 KBUILD_KCONFIG
 --------------------------------------------------
 Set the top-level Kconfig file to the value of this environment

Makefile

@@ -360,10 +360,11 @@ HOST_LFS_LIBS := $(shell getconf LFS_LIBS 2>/dev/null)
 HOSTCC       = gcc
 HOSTCXX      = g++
 KBUILD_HOSTCFLAGS   := -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 \
-		-fomit-frame-pointer -std=gnu89 $(HOST_LFS_CFLAGS)
-KBUILD_HOSTCXXFLAGS := -O2 $(HOST_LFS_CFLAGS)
-KBUILD_HOSTLDFLAGS  := $(HOST_LFS_LDFLAGS)
-KBUILD_HOSTLDLIBS   := $(HOST_LFS_LIBS)
+		-fomit-frame-pointer -std=gnu89 $(HOST_LFS_CFLAGS) \
+		$(HOSTCFLAGS)
+KBUILD_HOSTCXXFLAGS := -O2 $(HOST_LFS_CFLAGS) $(HOSTCXXFLAGS)
+KBUILD_HOSTLDFLAGS  := $(HOST_LFS_LDFLAGS) $(HOSTLDFLAGS)
+KBUILD_HOSTLDLIBS   := $(HOST_LFS_LIBS) $(HOSTLDLIBS)
 
 # Make variables (CC, etc...)
 AS		= $(CROSS_COMPILE)as