cmake: fixed "dist" target to use git instead of Mercurial.

CMakeLists.txt

@@ -252,12 +252,12 @@ else()
 endif()
 
 if(UNIX)
-    set(PHYSFS_TARBALL "${CMAKE_CURRENT_SOURCE_DIR}/../physfs-${PHYSFS_VERSION}.tar.bz2")
+    set(PHYSFS_TARBALL "${CMAKE_CURRENT_SOURCE_DIR}/../physfs-${PHYSFS_VERSION}.tar.gz")
 
     set(PHYSFS_TARGETNAME_DIST "dist" CACHE STRING "Name of 'dist' build target")
     add_custom_target(
         ${PHYSFS_TARGETNAME_DIST}
-        hg archive -t tbz2 "${PHYSFS_TARBALL}"
+        git archive --prefix="physfs-${PHYSFS_VERSION}/" --output="${PHYSFS_TARBALL}" HEAD
         WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
         COMMENT "Building source tarball '${PHYSFS_TARBALL}'..."
     )