fstools: update to latest git HEAD

20c16fc cmake: Make blockd link against libjson-c
92b4c2c libfstools: add basic documentation of mount functions

Signed-off-by: John Crispin <john@phrozen.org>

package/system/fstools/Makefile

@@ -12,9 +12,9 @@ PKG_RELEASE:=1
 
 PKG_SOURCE_PROTO:=git
 PKG_SOURCE_URL=$(LEDE_GIT)/project/fstools.git
-PKG_SOURCE_DATE:=2017-03-06
-PKG_SOURCE_VERSION:=98bbb5a068d6d32ef0ba7db5647a59fc67dfe75b
-PKG_MIRROR_HASH:=1e832d8aa1ce3560ed49d12f46ed17251e6f9b80e3a40408f4b048c308acde84
+PKG_SOURCE_DATE:=2017-03-29
+PKG_SOURCE_VERSION:=20c16fc5fec00fdae547f083a822a7f1bd67d143
+PKG_MIRROR_HASH:=fc6402291119744843b8482d3f02d5e819b92afe52f261fa30ed8bd26f4a62f1
 CMAKE_INSTALL:=1
 
 PKG_LICENSE:=GPL-2.0