component/apache: Remove use of which command in configure

Apache failed to compile in environments in which the which command was not present (such as Docker). This is fixed upstream (by using command -v instead) in https://github.com/apache/httpd/commit/05297d7b00f0cb1f20d3ff14f4409097df2615fe but not yet released.

This commit patches the configure script in a similar way, so that the which command is not used.