Move git submodules to a subdirectory

.gitmodules

@@ -1,6 +1,6 @@
 [submodule "wuffs-mirror-release-c"]
-	path = wuffs-mirror-release-c
+	path = submodules/wuffs-mirror-release-c
 	url = https://github.com/google/wuffs-mirror-release-c
 [submodule "liberty"]
-	path = liberty
+	path = submodules/liberty
 	url = https://git.janouch.name/p/liberty.git

fiv-io.c

@@ -84,7 +84,7 @@
 #define WUFFS_CONFIG__MODULE__PNG
 #define WUFFS_CONFIG__MODULE__TGA
 #define WUFFS_CONFIG__MODULE__ZLIB
-#include "wuffs-mirror-release-c/release/c/wuffs-v0.3.c"
+#include "submodules/wuffs-mirror-release-c/release/c/wuffs-v0.3.c"
 
 #include "fiv-io.h"
 

meson.build

@@ -236,7 +236,8 @@ if not win32
 		else
 			command = ['env', 'LC_ALL=C',
 				'asciidoc-release-version=' + meson.project_version(),
-				'awk', '-f', files('liberty/tools/asciiman.awk'), '@INPUT@']
+				'awk', '-f', files('submodules/liberty/tools/asciiman.awk'),
+				'@INPUT@']
 			man_capture = true
 		endif
 		custom_target('manpage for ' + page,