Add option USE_LIBGCC to link agains libgcc instead of liba softfloat implementation.

liba/Makefile.libgcc

@@ -0,0 +1,139 @@
+SFLAGS += -Iliba/include
+
+liba/src/external/sqlite/mem5.o: CFLAGS += -w
+
+objs += $(addprefix liba/src/, \
+  armv7m/setjmp.o \
+  armv7m/longjmp.o \
+  assert.o \
+  bzero.o \
+  ctype.o \
+  errno.o \
+  fpclassify.o \
+  fpclassifyf.o \
+  ieee754.o \
+  malloc.o \
+  memcmp.o \
+  memcpy.o \
+  memmove.o \
+  memset.o \
+  nearbyint.o \
+  nearbyintf.o \
+  strcmp.o \
+  strchr.o \
+  strlcpy.o \
+  strlen.o \
+  external/sqlite/mem5.o \
+)
+
+objs += $(addprefix liba/src/external/openbsd/, \
+  b_exp__D.o \
+  b_log__D.o \
+  b_tgamma.o \
+  e_acosf.o \
+  e_acoshf.o \
+  e_asinf.o \
+  e_atanhf.o \
+  e_atan2.o \
+  e_atan2f.o \
+  e_coshf.o \
+  e_expf.o \
+  e_fmod.o \
+  e_fmodf.o \
+  e_lgammaf_r.o \
+  e_log10f.o \
+  e_log2.o \
+  e_logf.o \
+  e_powf.o \
+  e_rem_pio2f.o \
+  e_scalb.o \
+  e_sinhf.o \
+  e_sqrtf.o \
+  k_cosf.o \
+  k_rem_pio2f.o \
+  k_sinf.o \
+  k_tanf.o \
+  s_asinhf.o\
+  s_atanf.o \
+  s_ceilf.o \
+  s_copysignf.o \
+  s_cosf.o \
+  s_erf.o \
+  s_expm1f.o\
+  s_fabsf.o \
+  s_floorf.o \
+  s_frexpf.o \
+  s_frexp.o \
+  s_log1pf.o \
+  s_logb.o \
+  s_modf.o \
+  s_modff.o \
+  s_rint.o \
+  s_roundf.o \
+  s_scalbnf.o \
+  s_signgam.o \
+  s_sinf.o \
+  s_tanf.o \
+  s_tanhf.o \
+  s_trunc.o \
+  s_truncf.o \
+  w_lgammaf.o \
+)
+
+objs += $(addprefix liba/src/external/openbsd/, \
+  e_acos.o \
+  e_acosh.o \
+  e_asin.o \
+  e_atanh.o \
+  e_cosh.o \
+  e_exp.o \
+  e_lgamma_r.o \
+  e_log.o \
+  e_log10.o \
+  e_pow.o \
+  e_rem_pio2.o \
+  e_sinh.o \
+  e_sqrt.o \
+  k_cos.o \
+  k_rem_pio2.o \
+  k_sin.o \
+  k_tan.o \
+  s_asinh.o \
+  s_atan.o \
+  s_ceil.o \
+  s_copysign.o \
+  s_cos.o \
+  s_expm1.o \
+  s_fabs.o \
+  s_floor.o \
+  s_log1p.o \
+  s_round.o \
+  s_scalbn.o \
+  s_sin.o \
+  s_tan.o \
+  s_tanh.o \
+  w_lgamma.o \
+)
+
+liba/src/external/openbsd/%.o: SFLAGS := -Iliba/src/external/openbsd/include $(SFLAGS)
+liba/src/external/openbsd/%.o: CFLAGS += -w
+
+tests += $(addprefix liba/test/, \
+  aeabi.c \
+  double.c \
+  ieee754.c \
+  long.c \
+  math.c \
+  setjmp.c \
+  stddef.c \
+  stdint.c \
+  strlcpy.c \
+)
+
+# The use of aeabi-rt could be made conditional to an AEABI target.
+# In practice we're always using liba on such a target.
+objs += $(addprefix liba/src/aeabi-rt/, \
+  atexit.o \
+)
+
+LDFLAGS+=-lgcc