make pkg-config hack cross-os compatible

Author: CamJN

Makefile

@@ -38,7 +38,7 @@ bump:
 	@ruby -e 'path = STDIN.read.strip;File.write(path, File.read(path).sub(/^(Version: +)([0-9]+)(?:(?:\.)([0-9]+)){1,}/){|s|"#{$$1}#{$$2}.#{$$3.to_i + 1}"})' <<< getargv++.pc
 	@ruby -e 'path = STDIN.read.strip;File.write(path, File.read(path).sub(/^(VERSION=)([0-9]+)(?:(?:\.)([0-9]+)){1,}/){|s|"#{$$1}#{$$2}.#{$$3.to_i + 1}"})' <<< Makefile-variables
 	@ruby -e 'path = STDIN.read.strip;File.write(path, File.read(path).sub(/^(PROJECT_NUMBER += +)([0-9]+)(?:(?:\.)([0-9]+)){1,}/){|s|"#{$$1}#{$$2}.#{$$3.to_i + 1}"})' <<< doxygen.conf
-	@env PKG_CONFIG_PATH=. pkg-config --define-variable=dep= --modversion getargv++
+	@env PKG_CONFIG_PATH=. pkg-config --define-variable=dep="''" --modversion getargv++
 
 tag:
 	git add -A