media-libs/libbpg: Honor AR, CC and CXX from the user environment

Signed-off-by: Lucio Sauer <watermanpaint@posteo.net>

media-libs/libbpg/files/libbpg-0.9.8-add-chost.patch

@@ -1,13 +0,0 @@
-diff --git a/Makefile b/Makefile
-index 8364e93..d3fc48f 100644
---- a/Makefile
-+++ b/Makefile
-@@ -27,7 +27,7 @@ CROSS_PREFIX:=x86_64-w64-mingw32-
- #CROSS_PREFIX=i686-w64-mingw32-
- EXE:=.exe
- else
--CROSS_PREFIX:=
-+CROSS_PREFIX:=${CHOST}-
- EXE:=
- endif
- 

media-libs/libbpg/files/libbpg-0.9.8-respect-compiler-driver.patch

@@ -0,0 +1,23 @@
+Honor AR, CC and CXX from the user enviroment instead of relying on
+${CHOST}-driver though it may be correct most of the time.
+Author: Lucio Sauer <watermanpaint@posteo.net>
+--- a/Makefile
++++ b/Makefile
+@@ -27,13 +27,13 @@ CROSS_PREFIX:=x86_64-w64-mingw32-
+ #CROSS_PREFIX=i686-w64-mingw32-
+ EXE:=.exe
+ else
+-CROSS_PREFIX:=
++CROSS_PREFIX:=${CHOST}-
+ EXE:=
+ endif
+ 
+-CC=$(CROSS_PREFIX)gcc
+-CXX=$(CROSS_PREFIX)g++
+-AR=$(CROSS_PREFIX)ar
++CC ?= $(CROSS_PREFIX)gcc
++CXX ?= $(CROSS_PREFIX)g++
++AR ?= $(CROSS_PREFIX)ar
+ EMCC=emcc
+ 
+ PWD:=$(shell pwd)

media-libs/libbpg/libbpg-0.9.8-r1.ebuild

@@ -34,12 +34,12 @@ KEYWORDS="~amd64 ~x86"
 IUSE="bpgview jctvc"
 
 PATCHES=(
-	"${FILESDIR}"/${P}-add-chost.patch
 	"${FILESDIR}"/${P}-add-fpic.patch
 	"${FILESDIR}"/${P}-backport-GNU-stack-note-fix.patch
 	"${FILESDIR}"/${P}-dont-strip-bins.patch
 	"${FILESDIR}"/${P}-remove-forced-options.patch
 	"${FILESDIR}"/${P}-remove-unused-cmake-var.patch
+	"${FILESDIR}"/${P}-respect-compiler-driver.patch
 	"${FILESDIR}"/${P}-respect-user-flags.patch
 )
 
@@ -81,12 +81,11 @@ EOF
 }
 
 src_compile() {
+	tc-export AR CC CXX
 	emake \
 		USE_X265=y \
 		$(usex bpgview USE_BPGVIEW=y '') \
-		$(usex jctvc USE_JCTVC=y '') \
-		CXX="$(tc-getCXX)" \
-		CC="$(tc-getCC)"
+		$(usex jctvc USE_JCTVC=y '')
 }
 
 src_install() {