[source] build: fix HOST_CONFIGURE_VARS placement

[LEDE Commits]

jow pushed a commit to source.git, branch master:
https://git.lede-project.org/83b6bfc2357458f219872f97ed9c4894106131a1

commit 83b6bfc2357458f219872f97ed9c4894106131a1
Author: Jo-Philipp Wich <jo at mein.io>
AuthorDate: Thu Jan 5 15:51:05 2017 +0100

    build: fix HOST_CONFIGURE_VARS placement
    
    Instead of passing HOST_CONFIGURE_VARS as arguments to the configure script,
    pass it as environment variables which brings the logic in line with the
    behaviour of package-defaults.mk.
    
    The change is needed since passing environment variables as configure
    parameters only works with GNU autoconf which evaluates command line arguments
    looking like variable assignments. Doing the same with non-autoconf configure
    scripts is not guaranteed to work since such scripts might terminate due to
    unknown argument errors.
    
    One example case is the cmake configure script which bails out when called
    as "./configure LDFLAGS=..." but not when called as "LDFLAGS=... ./configure".
    
    Also change the SHELL override to CONFIG_SHELL in the default
    HOST_CONFIGURE_VARS as the former is not properly propagated through the
    various GNU configure invocations since it gets lost when configure re-
    executes itself.
    
    A prior attempt to change the variable placement had to be reverted due to
    the missing SHELL -> CONFIG_SHELL change, leading to misgenerated libtool
    executables in various packages.
    
    Signed-off-by: Jo-Philipp Wich <jo at mein.io>
---
 include/host-build.mk | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/host-build.mk b/include/host-build.mk
index 4b4ffe4..5cfbdeb 100644
--- a/include/host-build.mk
+++ b/include/host-build.mk
@@ -53,7 +53,7 @@ HOST_CONFIGURE_VARS = \
 	CFLAGS="$(HOST_CFLAGS)" \
 	CPPFLAGS="$(HOST_CPPFLAGS)" \
 	LDFLAGS="$(HOST_LDFLAGS)" \
-	SHELL="$(SHELL)"
+	CONFIG_SHELL="$(SHELL)"
 
 HOST_CONFIGURE_ARGS = \
 	--target=$(GNU_HOST_NAME) \
@@ -75,9 +75,9 @@ define Host/Configure/Default
 	$(if $(HOST_CONFIGURE_PARALLEL),+)(cd $(HOST_BUILD_DIR)/$(3); \
 		if [ -x configure ]; then \
 			$(CP) $(SCRIPT_DIR)/config.{guess,sub} $(HOST_BUILD_DIR)/$(3)/ && \
+			$(HOST_CONFIGURE_VARS) \
 			$(2) \
 			$(HOST_CONFIGURE_CMD) \
-			$(HOST_CONFIGURE_VARS) \
 			$(HOST_CONFIGURE_ARGS) \
 			$(1); \
 		fi \