*/gcc6*: add objdump symlink [skip ci]

Without this symlink, lots of messages like this one appear while
compiling kernels:

/bin/sh: gcc6-armv6-alpine-linux-muslgnueabihf-objdump: not found

cross/gcc6-aarch64/APKBUILD

@@ -421,7 +421,7 @@ package() {
 		# Link binutils to gcc6-* (so 'CROSS_COMPILE=gcc6-...' works)
 		echo "Link binutils to gcc6-*"
 		mkdir -p "$pkgdir/usr/bin"
-		for i in "ld" "ar" "nm" "objcopy"; do
+		for i in "ld" "ar" "nm" "objcopy" "objdump"; do
 			ln -sv "/usr/bin/$CTARGET-$i" \
 				"$pkgdir/usr/bin/gcc6-$CTARGET-$i"
 		done

cross/gcc6-armhf/APKBUILD

@@ -421,7 +421,7 @@ package() {
 		# Link binutils to gcc6-* (so 'CROSS_COMPILE=gcc6-...' works)
 		echo "Link binutils to gcc6-*"
 		mkdir -p "$pkgdir/usr/bin"
-		for i in "ld" "ar" "nm" "objcopy"; do
+		for i in "ld" "ar" "nm" "objcopy" "objdump"; do
 			ln -sv "/usr/bin/$CTARGET-$i" \
 				"$pkgdir/usr/bin/gcc6-$CTARGET-$i"
 		done

cross/gcc6-x86_64/APKBUILD

@@ -421,7 +421,7 @@ package() {
 		# Link binutils to gcc6-* (so 'CROSS_COMPILE=gcc6-...' works)
 		echo "Link binutils to gcc6-*"
 		mkdir -p "$pkgdir/usr/bin"
-		for i in "ld" "ar" "nm" "objcopy"; do
+		for i in "ld" "ar" "nm" "objcopy" "objdump"; do
 			ln -sv "/usr/bin/$CTARGET-$i" \
 				"$pkgdir/usr/bin/gcc6-$CTARGET-$i"
 		done

main/gcc6/APKBUILD

@@ -401,7 +401,7 @@ package() {
 		# Link binutils to gcc6-* (so 'CROSS_COMPILE=gcc6-...' works)
 		echo "Link binutils to gcc6-*"
 		mkdir -p "$pkgdir/usr/bin"
-		for i in "ld" "ar" "nm" "objcopy"; do
+		for i in "ld" "ar" "nm" "objcopy" "objdump"; do
 			ln -sv "/usr/bin/$CTARGET-$i" \
 				"$pkgdir/usr/bin/gcc6-$CTARGET-$i"
 		done