feat: use PIC code model for shared libraries, fix shared library bugs

programs/libs/libmath/Makefile

@@ -11,6 +11,8 @@ NM := $(TOOLCHAIN_PREFIX)nm
 STRIP := $(TOOLCHAIN_PREFIX)strip
 
 # Compiler flags: freestanding, no stdlib
+# Build as PIE so library code remains valid when loaded into a slot-specific
+# base address by the kernel loader.
 override CXXFLAGS := \
     -std=gnu++20 \
     -g -O2 -pipe \
@@ -20,7 +22,7 @@ override CXXFLAGS := \
     -ffreestanding \
     -fno-stack-protector \
     -fno-stack-check \
-    -fno-PIC \
+    -fPIE \
     -fno-rtti \
     -fno-exceptions \
     -ffunction-sections \
@@ -55,7 +57,7 @@ LIBSRC := src/libmath.cpp
 
 all: $(OUTDIR)/$(LIBNAME).lib $(OUTDIR)/$(LIBNAME).lib.sym
 
-$(OUTDIR)/$(LIBNAME).lib: $(LIBSRC)
+$(OUTDIR)/$(LIBNAME).lib: $(LIBSRC) Makefile
 	@mkdir -p $(OUTDIR)
 	$(CXX) $(CXXFLAGS) -c $(LIBSRC) -o src/libmath.o
 	$(CXX) $(CXXFLAGS) $(LDFLAGS) src/libmath.o -o $@