Ability to detect Mesa drivers.

src/Magnum/Context.h

@@ -223,6 +223,9 @@ class MAGNUM_EXPORT Context {
             NVidia = 1 << 2,
             #endif
 
+            /** Mesa drivers on Linux */
+            Mesa = 1 << 3,
+
             #ifdef MAGNUM_TARGET_GLES
             /**
              * OpenGL ES implementation by ANGLE (translated to D3D), used by
@@ -230,7 +233,7 @@ class MAGNUM_EXPORT Context {
              * specification explicitly disallows exposing driver information
              * to the application, this check cannot be done reliably.
              */
-            ProbablyAngle = 1 << 3
+            ProbablyAngle = 1 << 4
             #endif
         };
 

src/Magnum/Implementation/driverSpecific.cpp

@@ -127,6 +127,7 @@ auto Context::detectedDriver() -> DetectedDrivers {
     _detectedDrivers = DetectedDrivers{};
 
     const std::string vendor = vendorString();
+    const std::string version = versionString();
 
     /* Apple has its own drivers */
     #ifndef CORRADE_TARGET_APPLE
@@ -140,6 +141,12 @@ auto Context::detectedDriver() -> DetectedDrivers {
     if(vendor.find("Intel") != std::string::npos)
         return *_detectedDrivers |= DetectedDriver::IntelWindows;
     #endif
+
+    #ifdef CORRADE_TARGET_UNIX
+    /* Mesa drivers */
+    if(version.find("Mesa") != std::string::npos)
+        return *_detectedDrivers |= DetectedDriver::Mesa;
+    #endif
     #endif
 
     #ifndef MAGNUM_TARGET_WEBGL