pakage/rpi-userland: add and install our bcm_host.pc

This allows pkg-config-aware packages to include headers from, and
link against Broadcom VideoCore host API library.

bcm_host.pc copied almost as-is from:
    http://cgit.collabora.com/git/user/pq/android-pc-files.git/tree/pkgconfig?h=raspberrypi
with only a fix to the prefix (we're using /usr).

[Peter: s/TARGET/STAGING/]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/rpi-userland/bcm_host.pc

@@ -0,0 +1,11 @@
+prefix=/usr
+exec_prefix=${prefix}
+libdir=${exec_prefix}/lib
+includedir=${prefix}/include
+
+Name: bcm_host
+Description: Broadcom VideoCore host API library
+Version: 1
+Libs: -L${libdir} -lbcm_host -lvcos -lvchiq_arm
+Cflags: -I${includedir} -I${includedir}/interface/vmcs_host/linux -I${includedir}/interface/vcos/pthreads -DUSE_VCHIQ_ARM
+

package/rpi-userland/rpi-userland.mk

@@ -14,7 +14,12 @@ RPI_USERLAND_CONF_OPT = -DVMCS_INSTALL_PREFIX=/usr
 define RPI_USERLAND_POST_TARGET_CLEANUP
     rm -Rf $(TARGET_DIR)/usr/src
 endef
-
 RPI_USERLAND_POST_INSTALL_TARGET_HOOKS += RPI_USERLAND_POST_TARGET_CLEANUP
 
+define RPI_USERLAND_POST_STAGING_PC_FILE
+	install -D -m 0644 package/rpi-userland/bcm_host.pc \
+		$(STAGING_DIR)/usr/lib/pkgconfig/bcm_host.pc
+endef
+RPI_USERLAND_POST_INSTALL_STAGING_HOOKS += RPI_USERLAND_POST_STAGING_PC_FILE
+
 $(eval $(cmake-package))