GitHub CI: parallel build of some deps

.github/scripts/Linux/prepare.sh

@@ -57,7 +57,7 @@ if [ -n "$SDK_URL" ]; then
                 mv /var/tmp/ntv2sdk* /var/tmp/ntv2sdk
                 cd /var/tmp/ntv2sdk/ajalibraries/ajantv2
                 export CXX='g++ -std=gnu++11'
-                make
+                make -j $(nproc)
         fi
 fi
 
@@ -77,7 +77,8 @@ git clone https://github.com/xanview/live555/
 cd live555
 git checkout 35c375
 ./genMakefiles linux-64bit
-sudo make install CPLUSPLUS_COMPILER="c++ -DXLOCALE_NOT_USED"
+make -j $(nproc) CPLUSPLUS_COMPILER="c++ -DXLOCALE_NOT_USED"
+sudo make install
 cd ..
 
 # Install cross-platform deps

.github/scripts/Windows/build_live555.sh

@@ -5,5 +5,5 @@ git clone https://github.com/xanview/live555/
 cd live555
 git checkout 35c375
 ./genMakefiles mingw
-make
+make -j $(nproc)
 

.github/scripts/Windows/install_spout.sh

@@ -5,7 +5,7 @@ git clone -b 2.006 --depth 1 https://github.com/leadedge/Spout2.git
 mkdir Spout2/SpoutSDK/Source/build
 cd Spout2/SpoutSDK/Source/build
 cmake -DBUILD_SHARED_LIBS=ON -G 'MSYS Makefiles' ..
-cmake --build .
+cmake --build . --parallel
 cp libSpout.dll /usr/local/bin
 cp libSpout.dll.a /usr/local/lib
 cd -