Update libloading dep to 0.7

Cherry-pick of https://github.com/KyleMayes/clang-sys/pull/123

Test: atest
Change-Id: I66610794a04947d412836dca3bd5d1f99769276e
diff --git a/Cargo.toml b/Cargo.toml
index 1da2ac4..4af7f4d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -31,7 +31,7 @@
 default-features = false
 
 [dependencies.libloading]
-version = "0.6"
+version = "0.7"
 optional = true
 [build-dependencies.glob]
 version = "0.3"