tests/driver_hih6130: fix 'absolute-value' error [backport 2021.01]

[aabadie]

Backport of #15964

Contribution description

This PR fixes a minor issues with a couple of calls of abs in tests/driver_hih6130. This function expect an int as input but a float is given. This leads to an error with gcc 10 (on riscv).
The proposed fix is to cast it to an int. It's untested but now it builds fine.

Testing procedure

• Green Murdock
• If someone has the sensor, it would nice to have this PR tested on it
• The build succeeds on gcc 10 riscv:

this PR:

$ BUILD_IN_DOCKER=1 make BOARD=atmega256rfr2-xpro -C tests/driver_hih6130/ --no-print-directory Launching build container using image "riot/riotbuild:latest".
docker run --rm --tty --user $(id -u) -v '/usr/share/zoneinfo/Europe/Paris:/etc/localtime:ro' -v '/work/riot/RIOT-review:/data/riotbuild/riotbase:delegated' -e 'RIOTBASE=/data/riotbuild/riotbase' -e 'CCACHE_BASEDIR=/data/riotbuild/riotbase' -e 'BUILD_DIR=/data/riotbuild/riotbase/build' -e 'RIOTPROJECT=/data/riotbuild/riotbase' -e 'RIOTCPU=/data/riotbuild/riotbase/cpu' -e 'RIOTBOARD=/data/riotbuild/riotbase/boards' -e 'RIOTMAKE=/data/riotbuild/riotbase/makefiles'      -e 'BOARD=atmega256rfr2-xpro'  -w '/data/riotbuild/riotbase/tests/driver_hih6130/' 'riot/riotbuild:latest' make 'BOARD=atmega256rfr2-xpro'    
Building application "tests_driver_hih6130" for "atmega256rfr2-xpro" with MCU "atmega256rfr2".

"make" -C /data/riotbuild/riotbase/boards/atmega256rfr2-xpro
"make" -C /data/riotbuild/riotbase/boards/common/atmega
"make" -C /data/riotbuild/riotbase/core
"make" -C /data/riotbuild/riotbase/cpu/atmega256rfr2
"make" -C /data/riotbuild/riotbase/cpu/atmega_common
"make" -C /data/riotbuild/riotbase/cpu/atmega_common/periph
"make" -C /data/riotbuild/riotbase/cpu/avr8_common
"make" -C /data/riotbuild/riotbase/cpu/avr8_common/avr_libc_extra
"make" -C /data/riotbuild/riotbase/drivers
"make" -C /data/riotbuild/riotbase/drivers/hih6130
"make" -C /data/riotbuild/riotbase/drivers/periph_common
"make" -C /data/riotbuild/riotbase/sys
"make" -C /data/riotbuild/riotbase/sys/auto_init
"make" -C /data/riotbuild/riotbase/sys/div
"make" -C /data/riotbuild/riotbase/sys/malloc_thread_safe
"make" -C /data/riotbuild/riotbase/sys/stdio_uart
"make" -C /data/riotbuild/riotbase/sys/xtimer
   text	   data	    bss	    dec	    hex	filename
  11390	    556	    984	  12930	   3282	/data/riotbuild/riotbase/tests/driver_hih6130/bin/atmega256rfr2-xpro/tests_driver_hih6130.elf

master:

$ BUILD_IN_DOCKER=1 make BOARD=hifive1b -C tests/driver_hih6130/ --no-print-directory 
Launching build container using image "riot/riotbuild:latest".
docker run --rm --tty --user $(id -u) -v '/usr/share/zoneinfo/Europe/Paris:/etc/localtime:ro' -v '/work/riot/RIOT-review:/data/riotbuild/riotbase:delegated' -e 'RIOTBASE=/data/riotbuild/riotbase' -e 'CCACHE_BASEDIR=/data/riotbuild/riotbase' -e 'BUILD_DIR=/data/riotbuild/riotbase/build' -e 'RIOTPROJECT=/data/riotbuild/riotbase' -e 'RIOTCPU=/data/riotbuild/riotbase/cpu' -e 'RIOTBOARD=/data/riotbuild/riotbase/boards' -e 'RIOTMAKE=/data/riotbuild/riotbase/makefiles'      -e 'BOARD=hifive1b'  -w '/data/riotbuild/riotbase/tests/driver_hih6130/' 'riot/riotbuild:latest' make 'BOARD=hifive1b'    
Building application "tests_driver_hih6130" for "hifive1b" with MCU "fe310".

/data/riotbuild/riotbase/tests/driver_hih6130/main.c: In function 'main':
/data/riotbuild/riotbase/tests/driver_hih6130/main.c:68:42: error: using integer absolute value function 'abs' when argument is of floating-point type 'float' [-Werror=absolute-value]
   68 |             (int)integral, (unsigned int)abs(fractional * 10000.f));
      |                                          ^~~
/data/riotbuild/riotbase/tests/driver_hih6130/main.c:71:42: error: using integer absolute value function 'abs' when argument is of floating-point type 'float' [-Werror=absolute-value]
   71 |             (int)integral, (unsigned int)abs(fractional * 10000.f));
      |                                          ^~~
cc1: all warnings being treated as errors
/data/riotbuild/riotbase/Makefile.base:107: recipe for target '/data/riotbuild/riotbase/tests/driver_hih6130/bin/hifive1b/application_tests_driver_hih6130/main.o' failed
make[1]: *** [/data/riotbuild/riotbase/tests/driver_hih6130/bin/hifive1b/application_tests_driver_hih6130/main.o] Error 1
/data/riotbuild/riotbase/Makefile.include:618: recipe for target 'application_tests_driver_hih6130.module' failed
make: *** [application_tests_driver_hih6130.module] Error 2

Issues/PRs references

Must be fixed before RIOT-OS/riotdocker#131 is merged and deployed on Murdock workers.

[aabadie]

Merged with #16140