amd64: fix GOT-indirect addressing bug in dictionary fast-path lookup

vm_find_word() and dict_find_word_heat_aware() reference the same extern
globals (sf_fc_list/sf_fc_count/sf_fc_cap) but GCC compiled cross-TU
references to them with GOT-indirect addressing (R_X86_64_REX_GOTPCRELX)
under -fPIC. This freestanding, statically-linked UEFI PE image has no
dynamic linker to populate a GOT, so those reads silently returned NULL
instead of the array's real address -- amd64-only, and exquisitely
sensitive to unrelated code-size changes since the choice between direct
and GOT-indirect addressing is a per-call-site GCC heuristic.

Fix: -fno-pic -fno-pie for amd64 only (ARCH_CFLAGS, overriding
COMMON_CFLAGS's -fPIC, which riscv64's -shared loader link still needs).
Also removes -DPLATFORM_TIME_NO_INLINE, a prior one-off workaround for
the identical bug applied to sf_monotonic_ns() specifically, now
redundant. Adds R_X86_64_PC32/R_X86_64_PLT32 handling to
elf_apply_relocations() as a robustness fix for the non-monolithic
split-build path (dead code for the current monolithic boot, where OVMF's
own PE loader relocates the image, not this loader).

Verified: all three architectures boot clean and pass the full item-4.2
Hermes self-test, including MSG-DELIVER-ALL, which previously triggered
the corruption on amd64 only. Write-up in FABRIC.md under item 4.2.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Makefile.starkernel

@@ -121,7 +121,18 @@ ifeq ($(ARCH),amd64)
         LD      := ld
         OBJCOPY := objcopy
     endif
-    ARCH_CFLAGS          := -m64 -march=x86-64 -mno-red-zone -DARCH_AMD64
+    # -fno-pic -fno-pie: this is a fixed-base, statically-linked freestanding
+    # image with no dynamic linker to populate a GOT at load time. -fPIC (set
+    # in COMMON_CFLAGS, needed by riscv64's -shared link pipeline) makes GCC
+    # emit R_X86_64_REX_GOTPCRELX (GOT-indirect) addressing for some cross-TU
+    # extern globals depending on per-call-site codegen heuristics; the "GOT
+    # slot" is just an unpopulated .bss cell here, so those reads silently
+    # return NULL instead of the real address. Root-caused 2026-08-06 via
+    # dict_find_word_heat_aware() reading sf_fc_count as NULL while
+    # vm_find_word() (same globals, same TU as the definition) read it
+    # correctly. These flags come after COMMON_CFLAGS on the command line so
+    # they win for amd64 only; riscv64/aarch64 keep -fPIC.
+    ARCH_CFLAGS          := -m64 -march=x86-64 -mno-red-zone -DARCH_AMD64 -fno-pic -fno-pie
     LOADER_LINKER_SCRIPT := linker/starkernel-loader-amd64.ld
     KERNEL_LINKER_SCRIPT := linker/starkernel-kernel-amd64.ld
 
@@ -173,10 +184,14 @@ LOADER_LD ?= $(LD)
 # ==============================================================================
 
 # Common flags for all arches / both loader and kernel.
-# -fPIC + -fvisibility=hidden: keeps all symbols local, prevents GOT references
-#   for internal function pointers (PE has no GOT).
-# -DPLATFORM_TIME_NO_INLINE: routes sf_monotonic_ns() through shim wrappers to
-#   avoid GOTPCREL relocations that crash at runtime in the PE environment.
+# -fPIC + -fvisibility=hidden: needed by riscv64's -shared loader link
+#   pipeline (amd64 overrides back to -fno-pic/-fno-pie in its ARCH_CFLAGS
+#   above -- see that comment for why: -fPIC made GCC emit GOT-indirect
+#   addressing for some cross-TU extern globals, and this freestanding image
+#   has no dynamic linker to populate a GOT, so those reads silently returned
+#   NULL. PLATFORM_TIME_NO_INLINE (removed 2026-08-06) was a symbol-specific
+#   workaround for the same underlying bug, made unnecessary once amd64 got
+#   the real fix; see FABRIC.md for the write-up).
 COMMON_CFLAGS := \
     -std=c99 -Wall -Werror -Wextra \
     -ffreestanding -nostdlib -fno-builtin \
@@ -184,8 +199,7 @@ COMMON_CFLAGS := \
     $(ARCH_CFLAGS) \
     -I$(KERNEL_INC) -Iinclude -Isrc \
     -include $(STARFORTH_CONFIG_HEADER) \
-    -DPARITY_MODE=$(PARITY_MODE) \
-    -DPLATFORM_TIME_NO_INLINE
+    -DPARITY_MODE=$(PARITY_MODE)
 
 VMCORE_CFLAGS_COMMON := \
     $(filter-out -I$(KERNEL_INC),$(COMMON_CFLAGS)) \