Fixes pkg-config file to have correct system libdir.

diff -aur glew-2.2.0/Makefile glew-2.2.0-alpine/Makefile
--- glew-2.2.0/Makefile	2020-03-15 11:53:59.000000000 +0000
+++ glew-2.2.0-alpine/Makefile	2022-01-28 02:42:23.773580331 +0000
@@ -144,7 +144,7 @@
 glew.pc: glew.pc.in
 	sed \
 		-e "s|@prefix@|$(GLEW_PREFIX)|g" \
-		-e "s|@libdir@|$(LIBDIR)|g" \
+		-e "s|@libdir@|/usr/lib|g" \
 		-e "s|@exec_prefix@|$(BINDIR)|g" \
 		-e "s|@includedir@|$(INCDIR)|g" \
 		-e "s|@version@|$(GLEW_VERSION)|g" \

diff -aur glew-2.2.0/config/Makefile.linux glew-2.2.0-alpine/config/Makefile.linux
--- glew-2.2.0/config/Makefile.linux	2020-03-15 11:53:59.000000000 +0000
+++ glew-2.2.0-alpine/config/Makefile.linux	2022-01-28 02:43:26.813582486 +0000
@@ -12,13 +12,8 @@
 ifeq (e2k,${M_ARCH})
   ARCH64 = true
 endif
-ifeq (${ARCH64},true)
-  LDFLAGS.EXTRA = -L/usr/X11R6/lib64 -L/usr/lib64
-  LIBDIR = $(GLEW_DEST)/lib64
-else
-  LDFLAGS.EXTRA = -L/usr/X11R6/lib -L/usr/lib
-  LIBDIR = $(GLEW_DEST)/lib
-endif
+LDFLAGS.EXTRA = -L/usr/X11R6/lib -L/usr/lib
+LIBDIR = $(GLEW_DEST)/lib
 LDFLAGS.GL = -lGL -lX11
 LDFLAGS.STATIC = -Wl,-Bstatic
 LDFLAGS.DYNAMIC = -Wl,-Bdynamic