openblas: add initial package

Initial draft PR is:
  https://github.com/openwrt/packages/pull/11894

This one is a bit more complete, and follows packaging practices.

For now, disabling builds on ARC and PowerPC. Will require more work to get
them going.
Explicitly disabling OpenMP support, so that it doesn't get picked by
accident.

Later we may use the `CPU_TYPE` parameter to tweak things a little further.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

libs/openblas/Makefile

@@ -0,0 +1,106 @@
+#
+# Copyright (C) 2021 Alexandru Ardelean <ardeleanalex@gmail.com>
+#
+
+include $(TOPDIR)/rules.mk
+
+PKG_NAME:=OpenBLAS
+PKG_VERSION:=0.3.15
+PKG_RELEASE:=$(AUTORELEASE)
+
+PKG_SOURCE:=OpenBLAS-$(PKG_VERSION).tar.gz
+PKG_SOURCE_URL:=https://github.com/xianyi/OpenBLAS/releases/download/v$(PKG_VERSION)/
+PKG_HASH:=30a99dec977594b387a17f49904523e6bc8dd88bd247266e83485803759e4bbe
+PKG_LICENSE:=BSD 3-Clause
+PKG_MAINTAINER:=Alexandru Ardelean <ardeleanalex@gmail.com>
+
+PKG_BUILD_PARALLEL:=1
+PKG_INSTALL:=1
+
+include $(INCLUDE_DIR)/package.mk
+
+define Package/openblas
+  SECTION:=libs
+  CATEGORY:=Libraries
+  TITLE:=An optimized library for BLAS (Basic Linear Algebra Subprograms)
+  URL:=https://www.openblas.net/
+  DEPENDS:= \
+       @!arc \
+       @!powerpc \
+       +INSTALL_GFORTRAN:libgfortran
+endef
+
+define Package/openblas/description
+  OpenBLAS is an optimized BLAS (Basic Linear Algebra Subprograms) library
+  based on GotoBLAS2 1.13 BSD version.
+endef
+
+define Package/openblas/config
+menu "Configuration"
+depends on PACKAGE_openblas
+
+config OPENBLAS_TARGET_OVERRIDE
+	string
+	prompt "Manual CPU target override (from the OpenBLAS TargetList.txt file)"
+
+endmenu
+endef
+
+OPENBLAS_TARGET=$(call qstrip,$(CONFIG_OPENBLAS_TARGET_OVERRIDE))
+
+ifeq ($(OPENBLAS_TARGET),)
+ifeq ($(ARCH),aarch64)
+  OPENBLAS_TARGET:=ARMV8
+else ifeq ($(ARCH),arm)
+  OPENBLAS_TARGET:=ARMV5
+else ifeq ($(ARCH),mips)
+  OPENBLAS_TARGET:=MIPS24K
+else ifeq ($(ARCH),mipsel)
+  OPENBLAS_TARGET:=MIPS24K
+else ifeq ($(ARCH),powerpc)
+  OPENBLAS_TARGET:=PPC440
+else ifeq ($(ARCH),mips64)
+  OPENBLAS_TARGET:=I6400
+else ifeq ($(ARCH),mips64el)
+  OPENBLAS_TARGET:=I6400
+else ifeq ($(ARCH),i386)
+  OPENBLAS_TARGET:=GENERIC
+else ifeq ($(ARCH),x86_64)
+  OPENBLAS_TARGET:=GENERIC
+endif
+endif # ifeq ($(OPENBLAS_TARGET),)
+
+ifeq ($(CONFIG_ARCH_64BIT),y)
+OPENBLAS_BINARY:=64
+else
+OPENBLAS_BINARY:=32
+endif
+
+MAKE_FLAGS += \
+	CROSS=1 \
+	HOSTCC=$(HOSTCC) \
+	CROSS_SUFFIX=$(TARGET_CROSS) \
+	BINARY=$(OPENBLAS_BINARY) \
+	NUM_THREADS=2 \
+	PREFIX=/usr \
+	COMMON_OPT="" \
+	TARGET=$(call qstrip,$(OPENBLAS_TARGET))
+
+ifneq ($(CONFIG_INSTALL_GFORTRAN),y)
+MAKE_FLAGS += NOFORTRAN=1
+endif
+
+define Build/InstallDev
+	$(INSTALL_DIR) $(1)/usr/lib/pkgconfig
+	$(INSTALL_DIR) $(1)/usr/include
+	$(CP) $(PKG_INSTALL_DIR)/usr/lib/* $(1)/usr/lib/
+	$(CP) $(PKG_INSTALL_DIR)/usr/include/* $(1)/usr/include/
+	$(CP) $(PKG_INSTALL_DIR)/usr/lib/pkgconfig/* $(1)/usr/lib/pkgconfig/
+endef
+
+define Package/openblas/install
+	$(INSTALL_DIR) $(1)/usr/lib
+	$(CP) $(PKG_INSTALL_DIR)/usr/lib/libopenblas*.so* $(1)/usr/lib/
+endef
+
+$(eval $(call BuildPackage,openblas))