rust-common: add LDFLAGS to 'build-rust-cc' wrapper

Although rust differs between compiling (--> 'rust-cc' wrapper) and
linking (--> 'rust-ccld' wrapper), some core crates are using only the
'rust-cc' wrapper to check for available compiler options [1] and
libraries [2].

Not having LDFLAGS can break the build in subtle ways.  E.g. 'cargo-native'
can fail to build with

|   = note: .../hosttools/ld: .../liblibz_sys-....rlib(deflate.o):
|     relocation R_X86_64_32S against hidden symbol `_length_code' can not be used when making a PIE object

because it does not find '-lz' (added by "DEPENDS = zlib") and builds
a static libz.a with missing PIC flags.

Add LDFLAGS to the 'build-rust-cc' wrapper as it is done already for
the target one.

[1] rust-lang/cc-rs#1322

[2] https://github.com/rust-lang/libz-sys/blob/12a32798c6bd18986cb5cd603359b03c96f0eb4c/build.rs#L228-L234

Signed-off-by: Enrico Scholz <[email protected]>
Signed-off-by: Mathieu Dubois-Briand <[email protected]>
Signed-off-by: Ross Burton <[email protected]>

Author: ensc

meta/classes-recipe/rust-common.bbclass

@@ -173,7 +173,7 @@ do_rust_create_wrappers () {
 	mkdir -p "${WRAPPER_DIR}"
 
 	# Yocto Build / Rust Host C compiler
-	create_wrapper_rust "${RUST_BUILD_CC}" "" "${CRATE_CC_FLAGS}" "${BUILD_CC}"
+	create_wrapper_rust "${RUST_BUILD_CC}" "" "${CRATE_CC_FLAGS}" "${BUILD_CC}" "${BUILD_LDFLAGS}"
 	# Yocto Build / Rust Host C++ compiler
 	create_wrapper_rust "${RUST_BUILD_CXX}" "" "${CRATE_CC_FLAGS}" "${BUILD_CXX}"
 	# Yocto Build / Rust Host linker