Fix build regression with DO_XSI_MATH disabled

Commit ea38f4d89 (math: add exception handling functionality) adds a
regression so that build configurations that have DO_C99_MATH enabled
and DO_XSI_MATH disabled will not link. This commit moves the files with
the bessel functions from DO_C99_MATH to DO_XSI_MATH. It looks like they
are not even contained in C99.

Signed-off-by: Ronald Wahl <ronald.wahl@raritan.com>

libm/Makefile.in

@@ -74,9 +74,6 @@ libm_CSRC := \
 	w_exp.c w_expf.c w_expl.c \
 	w_exp2.c w_exp2f.c w_exp2l.c \
 	w_exp10.c w_exp10f.c w_exp10l.c \
-	w_j0.c w_j0f.c w_j0l.c \
-	w_j1.c w_j1f.c w_j1l.c \
-	w_jn.c w_jnf.c w_jnl.c \
 	w_lgamma_r.c w_lgammaf_r.c w_lgammal_r.c \
 	w_lgamma.c w_lgammaf.c w_lgammal.c \
 	w_tgamma.c w_tgammaf.c w_tgammal.c \
@@ -267,7 +264,11 @@ FL_MOBJ := sqrtf.o
 endif
 
 ifeq ($(DO_XSI_MATH),y)
-libm_CSRC += e_j0.c e_j1.c e_jn.c
+libm_CSRC += \
+	e_j0.c e_j1.c e_jn.c \
+	w_j0.c w_j0f.c w_j0l.c \
+	w_j1.c w_j1f.c w_j1l.c \
+	w_jn.c w_jnf.c w_jnl.c
 endif
 
 # assume that arch specific versions are provided as single sources/objects