Problem with cross compiling libc.so.6 for armhf - inconsistent architectures - linux

Question

I am cross-compiling a go (golang) program to armhf. The program compiles successfully, but when I try to run it on an ARM board, it crashes with 'Illegal instruction' error.
Chasing down the problem, I am almost sure this is due to fact that glib.so.6 has inconsistent architecture.
Facts:
Host: ubuntu 18 (bionic), amd64
GCC: gcc version 7.5.0 (Ubuntu/Linaro 7.5.0-3ubuntu1~18.04)
I am using multiarch (armhf)
My Cortex-a5 ARM processor:
$ cat /proc/cpuinfo
Processor : ARMv7 Processor rev 1 (v7l)
BogoMIPS : 262.96
Features : swp half thumb fastmult vfp edsp vfpv3 vfpv3d16 tls vfpv4 <br>
CPU implementer : 0x41
CPU architecture: 7
CPU variant : 0x0
CPU part : 0xc05
CPU revision : 1
<br>
Hardware : SAMA5D3X-EK
Revision : 0000
Serial : 0000000000000000
All my armhf shared libraries have the following architecture:
$ readelf -A /lib/arm-linux-gnueabihf/ld-2.27.so
Attribute Section: aeabi
File Attributes
Tag_CPU_name: "7-A"
Tag_CPU_arch: v7
Tag_CPU_arch_profile: Application
Tag_ARM_ISA_use: Yes
Tag_THUMB_ISA_use: Thumb-2
Tag_FP_arch: VFPv3-D16
Tag_ABI_PCS_wchar_t: 4
Tag_ABI_FP_rounding: Needed
Tag_ABI_FP_denormal: Needed
Tag_ABI_FP_exceptions: Needed
Tag_ABI_FP_number_model: IEEE 754
Tag_ABI_align_needed: 8-byte
Tag_ABI_align_preserved: 8-byte, except leaf SP
Tag_ABI_enum_size: int
Tag_ABI_VFP_args: VFP registers
Tag_ABI_optimization_goals: Aggressive Speed
Tag_CPU_unaligned_access: v6
However, the armhf libc.so.6 is:
$ readelf -A /lib/arm-linux-gnueabihf/libc-2.27.so
Attribute Section: aeabi
File Attributes
Tag_CPU_name: "7-A"
Tag_CPU_arch: v7
Tag_CPU_arch_profile: Application
Tag_ARM_ISA_use: Yes
Tag_THUMB_ISA_use: Thumb-2
Tag_FP_arch: VFPv3
Tag_Advanced_SIMD_arch: NEONv1
Tag_ABI_PCS_wchar_t: 4
Tag_ABI_FP_rounding: Needed
Tag_ABI_FP_denormal: Needed
Tag_ABI_FP_exceptions: Needed
Tag_ABI_FP_user_exceptions: Needed
Tag_ABI_FP_number_model: IEEE 754
Tag_ABI_align_needed: 8-byte
Tag_ABI_enum_size: int
Tag_ABI_VFP_args: VFP registers
Tag_CPU_unaligned_access: v6
If I understand things correctly, this is wrong, as my processor does not support neon.
An old version of libc.so.6 on the ARM board looks as follows:
$ readelf -A /media/marek/sd/board/libc.so.6
Attribute Section: aeabi
File Attributes
Tag_CPU_name: "7-A"
Tag_CPU_arch: v7
Tag_CPU_arch_profile: Application
Tag_ARM_ISA_use: Yes
Tag_THUMB_ISA_use: Thumb-2
Tag_FP_arch: VFPv3-D16
Tag_ABI_PCS_wchar_t: 4
Tag_ABI_FP_denormal: Needed
Tag_ABI_FP_exceptions: Needed
Tag_ABI_FP_number_model: IEEE 754
Tag_ABI_align_needed: 8-byte
Tag_ABI_align_preserved: 8-byte, except leaf SP
Tag_ABI_enum_size: int
Tag_ABI_HardFP_use: Deprecated
Tag_ABI_VFP_args: VFP registers
Tag_CPU_unaligned_access: v6
Tag_DIV_use: Not allowed
Which looks consistent with the rest.
I wrote a trivial hello world program, and it crashes, too. But when I replace the armhf libc.so.6 with the old version on the board, it runs OK. However, I need a new version of libc (>= 2.25). Thus, it looks like it is sufficient to cross compile it from sources.
I am using configure with the following options:
../configure arm-linux-gnueabihf --prefix=pwd CFLAGS='-march=armv7-a -mfpu=vfpv3-d16 -g -O2 -w' LDFLAGS='-march=armv7-a -mfpu=vfpv3-d16 -g -w'
(also tried without LDFLAGS). All static libraries have the desired architecture but libc.so still has the wrong one (as above) - VFPv3 and NEONv1 are set). What am I doing wrong?