wasm: remove seemingly pointless -s flags

these libraries are handled by the configure system. i presume this to
be an artifact of an early version.

Change-Id: Ieee0554163a9fe296097d09e60a70719beee97b4
Reviewed-by: Lorn Potter <lorn.potter@gmail.com>

mkspecs/wasm-emscripten/qmake.conf

@@ -12,11 +12,6 @@ EMTERP_FLAGS = \
     -s ASSERTIONS=1 \
     --profiling-funcs
 
-EMCC_COMMON_CFLAGS = \
-    -s USE_LIBPNG=1 \
-    -s USE_FREETYPE=1 \
-    -s USE_ZLIB=1
-
 EMCC_COMMON_LFLAGS = \
     -s WASM=1 \
     -s FULL_ES2=1 \
@@ -45,9 +40,6 @@ QMAKE_COMPILER         += emscripten
 QMAKE_CC                = emcc
 QMAKE_CXX               = em++
 
-QMAKE_CFLAGS           += $$EMCC_COMMON_CFLAGS
-QMAKE_CXXFLAGS         += $$EMCC_COMMON_CFLAGS
-
 # Practical debugging setup:
 #    "-g4" preserves function names for stack traces
 #    "-Os" produces reasonably sized binaries