Significantly speed up compilation with GCC

Precompiled headers were broken because they weren't compiled with
the same -fPIC setting as the rest of the code.  Fix by just making
everything use -fPIC.

Makefile.in

@@ -92,7 +92,7 @@ VPATH := $(addprefix $(src_dir)/, $(sprojs_enabled))
 # These all appear on the command line, from lowest precedence to
 # highest.
 
-default-CFLAGS   := -DPREFIX=\"$(prefix)\" -Wall -Wno-unused -g -O2
+default-CFLAGS   := -DPREFIX=\"$(prefix)\" -Wall -Wno-unused -g -O2 -fPIC
 default-CXXFLAGS := $(default-CFLAGS) -std=c++11
 
 mcppbs-CPPFLAGS := @CPPFLAGS@

customext/customext.mk.in

@@ -8,6 +8,4 @@ customext_srcs = \
 	dummy_rocc.cc \
 	cflush.cc \
 
-customext_CFLAGS = -fPIC
-
 customext_install_shared_lib = yes

disasm/disasm.mk.in

@@ -1,5 +1,3 @@
-disasm_CFLAGS = -fPIC
-
 disasm_srcs = \
   disasm.cc \
   regnames.cc \

fesvr/fesvr.mk.in

@@ -15,8 +15,6 @@ fesvr_hdrs = \
   rfb.h \
   tsi.h \
 
-fesvr_CFLAGS = -fPIC
-
 fesvr_install_hdrs = $(fesvr_hdrs)
 
 fesvr_install_config_hdr = yes

riscv/riscv.mk.in

@@ -7,8 +7,6 @@ riscv_subproject_deps = \
 
 riscv_install_prog_srcs = \
 
-riscv_CFLAGS = -fPIC
-
 riscv_hdrs = \
 	abstract_device.h \
 	common.h \

softfloat/softfloat.mk.in

@@ -234,8 +234,6 @@ softfloat_c_srcs = \
 	ui64_to_f32.c \
 	ui64_to_f64.c \
 
-softfloat_CFLAGS = -fPIC
-
 softfloat_install_shared_lib = yes
 
 softfloat_test_srcs =