net-im/fractal: respect RUSTFLAGS

Set RUSTFLAGS like Mk/Uses/cargo.mk does to respect CC and LDFLAGS.

PR:		257621
Approved by:	Greg V <greg@unrelenting.technology> (maintainer)

net-im/fractal/Makefile

@@ -31,7 +31,8 @@ INSTALLS_ICONS=		yes
 # for the gettext-sys crate
 MAKE_ENV+=	GETTEXT_BIN_DIR=${LOCALBASE}/bin \
 		GETTEXT_LIB_DIR=${LOCALBASE}/lib \
-		GETTEXT_INCLUDE_DIR=${LOCALBASE}/include
+		GETTEXT_INCLUDE_DIR=${LOCALBASE}/include \
+		RUSTFLAGS="${RUSTFLAGS} -C linker=${CC:Q} ${LDFLAGS:C/.+/-C link-arg=&/}"
 
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