Fix GCC5 complaining about -Wunused-variable.

platform/default/image.cpp

@@ -11,6 +11,8 @@
 
 #include <mbgl/platform/default/image_reader.hpp>
 
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-variable"
 // Check png library version.
 const static bool png_version_check = []() {
     const png_uint_32 version = png_access_version_number();
@@ -22,7 +24,7 @@ const static bool png_version_check = []() {
     }
     return true;
 }();
-
+#pragma GCC diagnostic pop
 
 namespace mbgl {
 namespace util {

platform/default/sqlite3.cpp

@@ -5,6 +5,8 @@
 #include <cstring>
 #include <cstdio>
 
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-variable"
 // Check sqlite3 library version.
 const static bool sqliteVersionCheck = []() {
     if (sqlite3_libversion_number() / 1000000 != SQLITE_VERSION_NUMBER / 1000000) {
@@ -17,6 +19,7 @@ const static bool sqliteVersionCheck = []() {
 
     return true;
 }();
+#pragma GCC diagnostic pop 
 
 namespace mapbox {
 namespace sqlite {

src/mbgl/util/compression.cpp

@@ -6,6 +6,8 @@
 #include <cstring>
 #include <stdexcept>
 
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-variable"
 
 // Check zlib library version.
 const static bool zlibVersionCheck = []() {
@@ -20,6 +22,7 @@ const static bool zlibVersionCheck = []() {
     return true;
 }();
 
+#pragma GCC diagnostic pop
 
 namespace mbgl {
 namespace util {

src/mbgl/util/uv.cpp

@@ -4,12 +4,15 @@
 
 #include <uv.h>
 
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-variable"
 // Check libuv library version.
 const static bool uvVersionCheck = []() {
     const unsigned int version = uv_version();
     const unsigned int major = (version >> 16) & 0xFF;
     const unsigned int minor = (version >> 8) & 0xFF;
     const unsigned int patch = version & 0xFF;
+#pragma GCC diagnostic pop
 
 #ifndef UV_VERSION_PATCH
     // 0.10 doesn't have UV_VERSION_PATCH defined, so we "fake" it by using the library patch level.