flashrom: fix static build

Use $(TARGET_MAKE_ENV) to set $PATH so as to make sure Buildroot pkg-config is
used. This corrects pkg-config output, and fixes static build.

Fixes:
http://autobuild.buildroot.net/results/b6e/b6e9f3cb7fa8019e631c14d9c832174125ec64ba/
http://autobuild.buildroot.net/results/30c/30c83f9c60ac5c7359ddabdc1f190ab12433ae92/
http://autobuild.buildroot.net/results/2a5/2a5da78dd5b2922796e3010e4a0477cb9f6355cb/

and more.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/flashrom/flashrom.mk

@@ -7,12 +7,12 @@
 FLASHROM_VERSION = 0.9.8
 FLASHROM_SOURCE = flashrom-$(FLASHROM_VERSION).tar.bz2
 FLASHROM_SITE = http://download.flashrom.org/releases
-FLASHROM_DEPENDENCIES = pciutils libusb libusb-compat libftdi
+FLASHROM_DEPENDENCIES = pciutils libusb libusb-compat libftdi host-pkgconf
 FLASHROM_LICENSE = GPLv2+
 FLASHROM_LICENSE_FILES = COPYING
 
 define FLASHROM_BUILD_CMDS
-	$(MAKE) $(TARGET_CONFIGURE_OPTS) -C $(@D)
+	$(TARGET_MAKE_ENV) $(MAKE) $(TARGET_CONFIGURE_OPTS) -C $(@D)
 endef
 
 define FLASHROM_INSTALL_TARGET_CMDS