Makefile.inc: Add `-fno-pie` to `ADAFLAGS_common`

Building libgfxinit with Debian’s toolchain – latest test with *gnat-11*
11.2.0-13 from Debian sid/unstable – the build fails with the error
below.

    E: Invalid reloc type: 10
    E: Unable to create rmodule from 'build/cbfs/fallback/ramstage.debug'.

Debian’s toolchain is built without enabling PIE by default.

So, explicitly pass `-fno-pie` to `ADAFLAGS_common` to be independent
from how the toolchain was built.

TEST=*gnat* 11.2.0-13 successfully. builds
     purism/librem_cnl/variants/librem_mini with libgfxint.

     With the coreboot toolchain `make BUILD_TIMELESS=1` produces the
     same `build/coreboot.rom` for `BOARD_PURISM_LIBREM_MINI_V2=y` on
     top of commit 50251400d2 (sb/intel/common/firmware: Reword
     me_cleaner warning) with and without the change.
Change-Id: I6661937906d95c130c6099f598d61b21e958fd85
Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43759
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

Makefile.inc

@@ -444,6 +444,7 @@ ADAFLAGS_common += -pipe -g -nostdinc
 ADAFLAGS_common += -Wstrict-aliasing -Wshadow
 ADAFLAGS_common += -fno-common -fomit-frame-pointer
 ADAFLAGS_common += -ffunction-sections -fdata-sections
+ADAFLAGS_common += -fno-pie
 # Ada warning options:
 #
 #  a   Activate most optional warnings.

src/lib/gnat/Makefile.inc

@@ -13,6 +13,7 @@ ADAFLAGS_libgnat-$(1) := \
 	-I$$(src)/lib/gnat/ \
 	$$(GCC_ADAFLAGS_$(1)) \
 	-Werror \
+	-fno-pie \
 
 libgnat-$(1)-y += a-unccon.ads
 libgnat-$(1)-y += ada.ads