Fix current directory determination.

Makefile

@@ -40,7 +40,7 @@ override INSTALLPREFIX := $(CURDIR)/installdir
 override CMAKE_PREFIX := $(CURDIR)/cmake
 CMAKE := $(CMAKE_PREFIX)/bin/cmake
 override CMAKE_OPTS := --install-prefix $(INSTALLPREFIX) -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_INSTALL_RPATH='$$ORIGIN/../lib'
-override CONFIGURE := LDFLAGS="-Wl,-rpath,'\$$\$$ORIGIN/../lib' $$LDFLAGS" LD_LIBRARY_PATH=$PWD/installdir/lib:${LD_LIBRARY_PATH} ../configure --prefix=$(INSTALLPREFIX)
+override CONFIGURE := LDFLAGS="-Wl,-rpath,'\$$\$$ORIGIN/../lib' $$LDFLAGS" LD_LIBRARY_PATH=$(CURDIR)/installdir/lib:${LD_LIBRARY_PATH} ../configure --prefix=$(INSTALLPREFIX)
 
 # CMake setup
 ifeq ($(SYSTEM_CMAKE),)

README.md

@@ -9,7 +9,7 @@ Build
 First, install these dependencies (adapt accordingly for non-Debian distro):
 
 ```sh
-sudo apt-get install autotools-dev automake autoconf libtool patchelf curl
+sudo apt-get install autotools-dev automake autoconf libtool patchelf curl pkg-config
 ```
 
 Then followed by [all dependencies required by SDL](https://github.com/libsdl-org/SDL/blob/main/docs/README-linux.md#build-dependencies), but **not** the SDL itself.