Simplify the plumbing for re2.pc.

Change-Id: I6503b73978c9b2f4693422b62a74d4e1c75409c7
Reviewed-on: https://code-review.googlesource.com/c/re2/+/44491
Reviewed-by: Paul Wankadia <junyer@google.com>
diff --git a/Makefile b/Makefile
index f001f06..3571611 100644
--- a/Makefile
+++ b/Makefile
@@ -276,10 +276,8 @@
 	ln -sf libre2.$(SOEXTVER00) $(DESTDIR)$(libdir)/libre2.$(SOEXTVER)
 	ln -sf libre2.$(SOEXTVER00) $(DESTDIR)$(libdir)/libre2.$(SOEXT)
 	$(INSTALL_DATA) re2.pc $(DESTDIR)$(libdir)/pkgconfig/re2.pc
-	$(SED_INPLACE) -e "s#@prefix@#${prefix}#" $(DESTDIR)$(libdir)/pkgconfig/re2.pc
-	$(SED_INPLACE) -e "s#@exec_prefix@#${exec_prefix}#" $(DESTDIR)$(libdir)/pkgconfig/re2.pc
-	$(SED_INPLACE) -e "s#@includedir@#${includedir}#" $(DESTDIR)$(libdir)/pkgconfig/re2.pc
-	$(SED_INPLACE) -e "s#@libdir@#${libdir}#" $(DESTDIR)$(libdir)/pkgconfig/re2.pc
+	$(SED_INPLACE) -e "s#@includedir@#$(includedir)#" $(DESTDIR)$(libdir)/pkgconfig/re2.pc
+	$(SED_INPLACE) -e "s#@libdir@#$(libdir)#" $(DESTDIR)$(libdir)/pkgconfig/re2.pc
 
 testinstall: static-testinstall shared-testinstall
 	@echo
diff --git a/re2.pc b/re2.pc
index d66cf51..50fd637 100644
--- a/re2.pc
+++ b/re2.pc
@@ -1,5 +1,3 @@
-prefix=@prefix@
-exec_prefix=@exec_prefix@
 includedir=@includedir@
 libdir=@libdir@