[check-defs/symbols.sh] Drop empty-symbol lines

Fixes https://github.com/behdad/harfbuzz/issues/510

src/check-defs.sh

@@ -21,7 +21,7 @@ for def in $defs; do
 	lib=`echo "$def" | sed 's/[.]def$//;s@.*/@@'`
 	so=.libs/lib${lib}.so
 
-	EXPORTED_SYMBOLS="`nm "$so" | grep ' [BCDGINRSTVW] ' | grep -v ' _fini\>\| _init\>\| _fdata\>\| _ftext\>\| _fbss\>\| __bss_start\>\| __bss_start__\>\| __bss_end__\>\| _edata\>\| _end\>\| _bss_end__\>\| __end__\>\| __gcov_flush\>\| llvm_' | cut -d' ' -f3`"
+	EXPORTED_SYMBOLS="`nm "$so" | grep ' [BCDGINRSTVW] .' | grep -v ' _fini\>\| _init\>\| _fdata\>\| _ftext\>\| _fbss\>\| __bss_start\>\| __bss_start__\>\| __bss_end__\>\| _edata\>\| _end\>\| _bss_end__\>\| __end__\>\| __gcov_flush\>\| llvm_' | cut -d' ' -f3`"
 
 	if test -f "$so"; then
 

src/check-symbols.sh

@@ -20,7 +20,7 @@ for suffix in so dylib; do
 	so=.libs/libharfbuzz.$suffix
 	if ! test -f "$so"; then continue; fi
 
-	EXPORTED_SYMBOLS="`nm "$so" | grep ' [BCDGINRSTVW] ' | grep -v ' _fini\>\| _init\>\| _fdata\>\| _ftext\>\| _fbss\>\| __bss_start\>\| __bss_start__\>\| __bss_end__\>\| _edata\>\| _end\>\| _bss_end__\>\| __end__\>\| __gcov_flush\>\| ___gcov_flush\>\| llvm_\| _llvm_' | cut -d' ' -f3`"
+	EXPORTED_SYMBOLS="`nm "$so" | grep ' [BCDGINRSTVW] .' | grep -v ' _fini\>\| _init\>\| _fdata\>\| _ftext\>\| _fbss\>\| __bss_start\>\| __bss_start__\>\| __bss_end__\>\| _edata\>\| _end\>\| _bss_end__\>\| __end__\>\| __gcov_flush\>\| ___gcov_flush\>\| llvm_\| _llvm_' | cut -d' ' -f3`"
 
 	prefix=`basename "$so" | sed 's/libharfbuzz/hb/; s/-/_/g; s/[.].*//'`