env: Fix operation of 'make environ'

This was broken by the recent environment refactoring. Specifically:

$  make environ
scripts/Makefile.build:59: tools/environ/Makefile: No such file or directory
make[1]: *** No rule to make target 'tools/environ/Makefile'.  Stop.
make: *** [Makefile:1469: environ] Error 2

Fix this by updating the Makefile and adjusting the #include filesnames in
two C files.

Fixes: ec74f5f (Makefile: Rename 'env' target to 'environ')
Reported-by: Måns Rullgård <mans@mansr.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/Makefile b/Makefile
index 020ebd5..70971b1 100644
--- a/Makefile
+++ b/Makefile
@@ -1465,14 +1465,14 @@
 		false; \
 	fi
 
-environ: scripts_basic
+envtools: scripts_basic
 	$(Q)$(MAKE) $(build)=tools/env
 
 tools-only: scripts_basic $(version_h) $(timestamp_h)
 	$(Q)$(MAKE) $(build)=tools
 
 tools-all: export HOST_TOOLS_ALL=y
-tools-all: environ tools ;
+tools-all: envtools tools ;
 
 cross_tools: export CROSS_BUILD_TOOLS=y
 cross_tools: tools ;