math: Fix build system for old config.mk

There are new make variables WANT_EXP10_TESTS and
WANT_SIMD_EXCEPT, make sure unset variables work
too on top of the 0 and 1 settings, this way old
config.mk still builds unmodified.

Author: nsz-arm

math/Dir.mk

@@ -96,7 +96,7 @@ build/bin/%.sh: $(S)/test/%.sh
 	cp $< $@
 
 math-tests := $(wildcard $(S)/test/testcases/directed/*.tst)
-ifeq ($(WANT_EXP10_TESTS),0)
+ifneq ($(WANT_EXP10_TESTS),1)
 math-tests := $(filter-out %exp10.tst, $(math-tests))
 endif
 math-rtests := $(wildcard $(S)/test/testcases/random/*.tst)

math/test/runulp.sh

@@ -72,7 +72,7 @@ t pow  0x1.ffffffffffff0p-1  0x1.0000000000008p0 x 0x1p60 0x1p68 50000
 t pow  0x1.ffffffffff000p-1  0x1p0 x 0x1p50 0x1p52 50000
 t pow -0x1.ffffffffff000p-1 -0x1p0 x 0x1p50 0x1p52 50000
 
-if [ $WANT_EXP10_TESTS -eq 1 ]; then
+if [ "$WANT_EXP10_TESTS" = 1 ]; then
 L=0.02
 t exp10   0                   0x1p-47             5000
 t exp10  -0                  -0x1p-47             5000
@@ -156,7 +156,7 @@ done
 
 # vector functions
 
-if [ $WANT_SIMD_TESTS -eq 1 ]; then
+if [ "$WANT_SIMD_TESTS" = 1 ]; then
 
 Ldir=0.5
 r='n'