package/openblas: fix some x86 32bit builds

OpenBLAS Makefile normally needs to explicitly define the CPU
architecture size (32 or 64bit) in the BINARY macro. See [1].

When an architecture supports both 64 and 32bit, the 32bit support
is sometimes implemented in OpenBLAS by overriding a fallback to an
anterior architecture. For example, if the build target architecture
is x86 Haswell 32bit, OpenBLAS build will override the arch to
Nehalem. See [2].

If the BINARY macro is undefined, the 32bit fallback will not happen,
sometimes leading to a link failure, with output:

    i686-buildroot-linux-gnu/bin/ar: strmm_kernel_LN.o: No such file or directory

This commit fixes those issues by explicitly defining the BINARY
macro. This issue has also been discussed upstream in [3] and [4].

Note: this issue was not introduced recently ([3] dates back from 2015),
and was also see in previous package version, for example in [5].

Fixes:
http://autobuild.buildroot.net/results/e1e/e1e2034a78799abe1bd28b036fa6f7d13322e42f

[1] https://github.com/xianyi/OpenBLAS/blob/v0.3.24/Makefile.rule#L50
[2] https://github.com/xianyi/OpenBLAS/blob/v0.3.24/Makefile.system#L113
[3] OpenMathLib/OpenBLAS#657
[4] OpenMathLib/OpenBLAS#1106
[5] http://autobuild.buildroot.net/results/5cd/5cdccd106b1de275ac75c39783e536107a31651f

Signed-off-by: Julien Olivain <ju.o@free.fr>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
(cherry picked from commit eb4f5a2)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/openblas/openblas.mk

@@ -49,6 +49,12 @@ ifeq ($(BR2_STATIC_LIBS),y)
 OPENBLAS_MAKE_OPTS += NO_SHARED=1
 endif
 
+ifeq ($(BR2_ARCH_IS_64),y)
+OPENBLAS_MAKE_OPTS += BINARY=64
+else
+OPENBLAS_MAKE_OPTS += BINARY=32
+endif
+
 # binutils version <= 2.23.2 has a bug
 # (https://sourceware.org/bugzilla/show_bug.cgi?id=14887) where
 # whitespaces in ARM register specifications such as [ r1, #12 ] or [