gnu: appimage: New packages for the appimage runtime.

* gnu/packages/appimage.scm
(gnu packages appimage): New module.
(appimage-type2-runtime): New variable.
* gnu/packages/file-systems.scm (squashfuse-for-appimage):
New variable.
* gnu/packages/linux.scm (fuse-for-appimage): New variable.

Change-Id: I857a8eb5399a6a493e52db70b6c8cf0c71360930
Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu/packages/file-systems.scm

@@ -2059,6 +2059,27 @@ almost all features of the SquashFS format, yet is still fast and
 memory-efficient.")
     (license license:bsd-2)))
 
+(define-public squashfuse-for-appimage
+    (package
+      (inherit squashfuse)
+      (arguments
+       (list
+        #:configure-flags
+        #~'("CFLAGS=-ffunction-sections -fdata-sections -Os -no-pie"
+            "LDFLAGS=-static")
+        #:phases
+        #~(modify-phases %standard-phases
+            (add-after 'install 'install-private-headers
+              (lambda _
+                (install-file "fuseprivate.h"
+                              (string-append #$output
+                                             "/include/squashfuse/")))))))
+      (inputs (list fuse-for-appimage
+                    `(,zstd "lib")
+                    `(,zstd "static")
+                    `(,zlib "out")
+                    `(,zlib "static")))))
+
 (define-public tmsu
   (package
     (name "tmsu")