fix: the config file extension is not required to be .toml

.cargo/config

@@ -0,0 +1 @@
+config.toml

.cargo/config.toml

@@ -0,0 +1,8 @@
+# These flags are the only way to tell cargo to add directories to the library
+# search path.  When `build.rs` script is used, this is not needed since the
+# script will set the library paths correctly.  But when it isn't used,
+# something still needs to produce these flags.  With cargo, this is the only
+# way.
+[build]
+rustflags=["-L", "/usr/local/lib"]
+rustdocflags=["-L", "/usr/local/lib"]