Only load a dependent library when it has an expected symbol.

Bug 18752589

Change-Id: Ic42be261dc101810e6363c4823620d6c827c7975
Reviewed-on: https://swiftshader-review.googlesource.com/2880
Tested-by: Nicolas Capens <capn@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>

src/OpenGL/libGLES_CM/libGLES_CM.cbp

diff --git a/src/OpenGL/libGLES_CM/libGLES_CM.cbp b/src/OpenGL/libGLES_CM/libGLES_CM.cbp
index c0cbc51..f0769f6 100644
--- a/src/OpenGL/libGLES_CM/libGLES_CM.cbp
+++ b/src/OpenGL/libGLES_CM/libGLES_CM.cbp
@@ -115,6 +115,7 @@
 			<Add option="-fexceptions" />
 			<Add option="-fno-operator-names" />
 			<Add option="-msse2" />
+			<Add option="-fvisibility=protected" />
 			<Add option="-D__STDC_LIMIT_MACROS" />
 			<Add option="-D__STDC_CONSTANT_MACROS" />
 			<Add directory="./../" />