Fix shell syntax error

Fixes https://github.com/harfbuzz/harfbuzz/issues/1612

src/check-symbols.sh

@@ -26,7 +26,7 @@ for soname in harfbuzz harfbuzz-subset harfbuzz-icu harfbuzz-gobject; do
 		symprefix=
 		if test $suffix = dylib; then symprefix=_; fi
 
-		EXPORTED_SYMBOLS="`nm "$so" | grep ' [BCDGINRST] .' | grep -v " $symprefix\\($IGNORED_SYMBOLS\\>\\)" | cut -d' ' -f3 | c++filt`"
+		EXPORTED_SYMBOLS=`nm "$so" | grep ' [BCDGINRST] .' | grep -v " $symprefix\\($IGNORED_SYMBOLS\\>\\)" | cut -d' ' -f3 | c++filt`
 
 		prefix=$symprefix`basename "$so" | sed 's/libharfbuzz/hb/; s/-/_/g; s/[.].*//'`