Adds support for non pkg-config tpm2-tss installs.

- Adds support for specifying path to the tpm2-tss libraries and
  header files using the environment variable ```TPM2_TSS_PATH```.
  The specified path is expected to have the following layout:
  | -> <Specified path>
  |    | -> include
  |       | -> tss2
  |           | -> tss2_esys.h
  |
  |    | -> lib
  |        | -> tss2_esys.lib (or .so)

Signed-off-by: Jesper Brynolf <jesper.brynolf@gmail.com>

tss-esapi-sys/Cargo.toml

@@ -13,7 +13,7 @@ documentation = "https://docs.rs/crate/tss-esapi-sys"
 links = "tss2-esys"
 
 [build-dependencies]
-bindgen = { version = "0.66.1", optional = true }
+bindgen = { version = "0.69.1", optional = true }
 pkg-config = "0.3.18"
 target-lexicon = "0.12.0"
 cfg-if = "1.0.0"