fix(boards.txt): remove warnings raised by arduino-lint

even if those pattern properties are present thanks other patterns
to shorten some recipe lines.

WARNING: recipe.c.o.pattern property value does not contain a {compiler.c.extra_flags} reference. This is necessary to
         allow the user to customize the compiler command. (Rule PF057)
WARNING: recipe.S.o.pattern property value does not contain a {compiler.S.extra_flags} reference. This is necessary to
         allow the user to customize the compiler command. (Rule PF063)

Signed-off-by: Frederic Pillon <frederic.pillon@st.com>

Author: fpistm

platform.txt

@@ -71,12 +71,6 @@ compiler.elf2hex.extra_flags=
 compiler.arm.cmsis.c.flags="-I{runtime.tools.CMSIS-5.7.0.path}/CMSIS/Core/Include/" "-I{build.system.path}/Drivers/CMSIS/Device/ST/{build.series}/Include/" "-I{build.system.path}/Drivers/CMSIS/Device/ST/{build.series}/Source/Templates/gcc/" "-I{runtime.tools.CMSIS-5.7.0.path}/CMSIS/DSP/Include" "-I{runtime.tools.CMSIS-5.7.0.path}/CMSIS/DSP/PrivateInclude"
 compiler.arm.cmsis.ldflags="-L{runtime.tools.CMSIS-5.7.0.path}/CMSIS/DSP/Lib/GCC/" -l{build.cmsis_lib_gcc}
 
-# Groups some extra_flags properties to shorten recipe lines and allows arduino-cli to
-# override some standard Arduino build property with a custom value.
-build.g_extra_flags={build.st_extra_flags} {build.extra_flags}
-compiler.c.g_extra_flags={compiler.c.st_extra_flags} {compiler.c.extra_flags}
-compiler.S.g_extra_flags={compiler.S.st_extra_flags} {compiler.S.extra_flags}
-
 # USB Flags
 # ---------
 build.usb_flags=-DUSBCON {build.usb_speed} -DUSBD_VID={build.vid} -DUSBD_PID={build.pid} -DHAL_PCD_MODULE_ENABLED
@@ -128,13 +122,13 @@ recipe.hooks.prebuild.1.pattern.windows="{runtime.tools.STM32Tools.path}/win/bus
 # ---------------------
 
 ## Compile c files
-recipe.c.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.c.flags} {build.info.flags} {compiler.c.g_extra_flags} {build.g_extra_flags} {compiler.arm.cmsis.c.flags} {includes} "{source_file}" -o "{object_file}"
+recipe.c.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.c.flags} {build.info.flags} {compiler.c.st_extra_flags} {compiler.c.extra_flags} {build.st_extra_flags} {build.extra_flags} {compiler.arm.cmsis.c.flags} {includes} "{source_file}" -o "{object_file}"
 
 ## Compile c++ files
-recipe.cpp.o.pattern="{compiler.path}{compiler.cpp.cmd}" {compiler.cpp.flags} {build.info.flags} {compiler.cpp.extra_flags} {build.g_extra_flags} {compiler.arm.cmsis.c.flags} {includes} "{source_file}" -o "{object_file}"
+recipe.cpp.o.pattern="{compiler.path}{compiler.cpp.cmd}" {compiler.cpp.flags} {build.info.flags} {compiler.cpp.extra_flags} {build.st_extra_flags} {build.extra_flags} {compiler.arm.cmsis.c.flags} {includes} "{source_file}" -o "{object_file}"
 
 ## Compile S files
-recipe.S.o.pattern="{compiler.path}{compiler.S.cmd}" {compiler.S.flags} {build.info.flags} {compiler.S.g_extra_flags} {build.g_extra_flags} {compiler.arm.cmsis.c.flags} {includes} "{source_file}" -o "{object_file}"
+recipe.S.o.pattern="{compiler.path}{compiler.S.cmd}" {compiler.S.flags} {build.info.flags} {compiler.S.st_extra_flags} {compiler.S.extra_flags} {build.st_extra_flags} {build.extra_flags} {compiler.arm.cmsis.c.flags} {includes} "{source_file}" -o "{object_file}"
 
 ## Create archives
 recipe.ar.pattern="{compiler.path}{compiler.ar.cmd}" {compiler.ar.flags} {compiler.ar.extra_flags} "{archive_file_path}" "{object_file}"