Add support for s390x architecture

Signed-off-by: Julian Ruess <julianr@linux.ibm.com>

Makefile

@@ -29,6 +29,7 @@ BUILD_FLAGS    := -a -ldflags "-s -w -X main.version=$(VERSION) -X main.revision
 
 BINARY32       := fzf-$(GOOS)_386
 BINARY64       := fzf-$(GOOS)_amd64
+BINARYS390     := fzf-$(GOOS)_s390x
 BINARYARM5     := fzf-$(GOOS)_arm5
 BINARYARM6     := fzf-$(GOOS)_arm6
 BINARYARM7     := fzf-$(GOOS)_arm7
@@ -43,6 +44,8 @@ ifeq ($(UNAME_M),x86_64)
 	BINARY := $(BINARY64)
 else ifeq ($(UNAME_M),amd64)
 	BINARY := $(BINARY64)
+else ifeq ($(UNAME_M),s390x)
+	BINARY := $(BINARYS390)
 else ifeq ($(UNAME_M),i686)
 	BINARY := $(BINARY32)
 else ifeq ($(UNAME_M),i386)
@@ -132,6 +135,8 @@ target/$(BINARY32): $(SOURCES)
 target/$(BINARY64): $(SOURCES)
 	GOARCH=amd64 $(GO) build $(BUILD_FLAGS) -o $@
 
+target/$(BINARYS390): $(SOURCES)
+	GOARCH=s390x $(GO) build $(BUILD_FLAGS) -o $@
 # https://github.com/golang/go/wiki/GoArm
 target/$(BINARYARM5): $(SOURCES)
 	GOARCH=arm GOARM=5 $(GO) build $(BUILD_FLAGS) -o $@