Fix compilation on Linux + update build requirements

BUILDING

@@ -31,7 +31,10 @@ Microsoft Windows
 Linux / Unix
 ----------------------------------------------------------------------------------
 
-  There is no required extra dependency, you only need Qt tools.
+  You need to have Qt 4 (>= 4.7) or Qt 5 development libraries, pkg-config is
+  highly recommended to correctly detect QtWebKit version.
+  Next compulsory requirement is OpenSSL (libcrypto). X11 libraries are also
+  required unless you specify NO_X11 build option.
 
   To build spellcheck plugin, you need:
      - QtWebKit 2.3 or higher

README.md

@@ -41,12 +41,14 @@ and you have read the [BUILDING](https://github.com/QupZilla/qupzilla/blob/maste
 
 **Linux**  
 
- * pkg-config is optional (to correctly detect versions of QtWebKit)
+ * OpenSSL (libcrypto) is required
+ * pkg-config is recommended (to correctly detect versions of QtWebKit)
  * pkg-config is required for Hunspell spellcheck
  * Hunspell development package for spellcheck
  * QtWebKit 2.3 is needed to have support for spellcheck
  
 **Windows**  
+ * OpenSSL (libeay32) is required
  * QtWebKit 2.3 is required
  * Hunspell library is required for spellcheck
 

src/lib/lib.pro

@@ -504,6 +504,8 @@ isEqual(QT_MAJOR_VERSION, 5) {
 win32 {
     HEADERS += other/registerqappassociation.h
     SOURCES += other/registerqappassociation.cpp
+
+    LIBS += -llibeay32
 }
 
 mac {
@@ -516,7 +518,7 @@ mac {
     LIBS += -framework CoreServices
 }
 
-LIBS += -llibeay32
+LIBS += -lcrypto
 
 message(===========================================)
 message( Using following defines:)