subprojects: Switch inih to a properly managed git submodule

This allows us to correctly manage inih version by manually updating it,
as opposed to relying on `HEAD` which will render each build unable to
reproduce across changes.

Additionally with submodules we can look to distribute complete tarballs
of the repository to facilitate build systems that ban networking for
security reasons (i.e. Solus).

Signed-off-by: Ikey Doherty <ikey@solus-project.com>

.gitignore

@@ -1,3 +1,2 @@
 build/
-subprojects/inih/
 *.swp

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "subprojects/inih"]
+	path = subprojects/inih
+	url = https://github.com/FeralInteractive/inih.git

subprojects/inih

@@ -0,0 +1 @@
+Subproject commit 745ada6724038cde32ff6390b32426cbdd5e532b