deps: "+=" implies an added space

recipes-deps/curl/curl_%.bbappend

@@ -17,4 +17,4 @@
 #	--enable-hidden-symbols \
 #"
 
-CFLAGS +=" -fPIC"
+CFLAGS += "-fPIC"

recipes-deps/zlib/zlib_%.bbappend

@@ -1,3 +1,3 @@
 # cargo tries to build a shared object using several static objects, one of
 # which includes the contenst of zlib (zutil.o)
-CFLAGS += " -fPIC"
+CFLAGS += "-fPIC"