Add extra arg & env var support to linux-build.sh

- You can now provide a full $CONFIG env var to directly set "debug_x64"
  or another value of your choice.
- You can now provide an extra argument "release" or "debug".
- Both parameters (arch, build type) now have input validation.

linux-build.sh

@@ -7,13 +7,44 @@ else
     PREMAKE5=utils/premake5
 fi
 
+ENV_CONFIG=$CONFIG
+DEFAULT=2
+
+# Debug vs Release
+if [[ $2 = "release" ]] || [[ $2 = "debug" ]]; then
+    CONFIG=$2
+elif [[ $2 != "" ]]; then
+    printf "Unknown build type \"$2\" provided\n"
+    exit 1
+else
+    CONFIG=release
+    ((DEFAULT--))
+fi
+
 # 32bit vs 64bit
-if [[ $1 = "32" ]]; then
-    CONFIG=release_x86
+if [[ $1 = "32" ]] || [[ $1 = "x86" ]]; then
+    CONFIG=${CONFIG}_x86
+elif [[ $1 = "64" ]] || [[ $1 = "x64" ]]; then
+    CONFIG=${CONFIG}_x64
+elif [[ $1 != "" ]]; then
+    printf "Unknown architecture \"$1\" provided\n"
+    exit 1
 else
-    CONFIG=release_x64
+    CONFIG=${CONFIG}_x64
+    ((DEFAULT--))
 fi
 
+# Only apply $CONFIG from environment if no args provided
+if [[ $ENV_CONFIG != "" ]]; then
+    if [[ $DEFAULT != 0 ]]; then
+        printf "Ignoring provided \$CONFIG environment variable, "
+    else
+        CONFIG=$ENV_CONFIG
+    fi
+fi
+
+printf "\$CONFIG=$CONFIG\n"
+
 # Clean old build files
 rm -Rf Build/
 rm -Rf Bin/
@@ -29,5 +60,4 @@ else
 fi
 
 # Build!
-cd Build/
-make -j$NUM_CORES config=$CONFIG all
+make -C Build/ -j$NUM_CORES config=$CONFIG all