Use prefix BORING_BSSL_ for all boringssl env variables

This means BORING_SSL_PRECOMPILED_BCM_O is now
BORING_BSSL_PRECOMPILED_BCM_O.

Prefix BORING_BSSL_ has been chosen because that's the
one that is used the most among all the variables
the build script uses.

boring-sys/build/config.rs

@@ -112,7 +112,7 @@ impl Env {
             path: var("BORING_BSSL_PATH").map(Into::into),
             include_path: var("BORING_BSSL_INCLUDE_PATH").map(Into::into),
             source_path: var("BORING_BSSL_SOURCE_PATH").map(Into::into),
-            precompiled_bcm_o: var("BORING_SSL_PRECOMPILED_BCM_O").map(Into::into),
+            precompiled_bcm_o: var("BORING_BSSL_PRECOMPILED_BCM_O").map(Into::into),
             debug: var("DEBUG"),
             opt_level: var("OPT_LEVEL"),
             android_ndk_home: var("ANDROID_NDK_HOME").map(Into::into),

boring-sys/build/main.rs

@@ -529,7 +529,7 @@ fn link_in_precompiled_bcm_o(config: &Config) {
 
     let bssl_dir = built_boring_source_path(config);
     let bcm_o_src_path = config.env.precompiled_bcm_o.as_ref()
-        .expect("`fips-link-precompiled` requires `BORING_SSL_PRECOMPILED_BCM_O` env variable to be specified");
+        .expect("`fips-link-precompiled` requires `BORING_BSSL_PRECOMPILED_BCM_O` env variable to be specified");
 
     let libcrypto_path = bssl_dir
         .join("build/crypto/libcrypto.a")

boring/src/lib.rs

@@ -46,7 +46,7 @@
 //! ## Linking current BoringSSL version with precompiled FIPS-validated module (`bcm.o`)
 //! It's possible to link latest supported version of BoringSSL with FIPS-validated crypto module
 //! (`bcm.o`). To enable this compilation option one should enable `fips-link-precompiled`
-//! compilation feature and provide a `BORING_SSL_PRECOMPILED_BCM_O` env variable with a path to the
+//! compilation feature and provide a `BORING_BSSL_PRECOMPILED_BCM_O` env variable with a path to the
 //! precompiled FIPS-validated `bcm.o` module.
 //!
 //! # Optional patches