build: Fix missing variable quotes

build: Fix missing variable quotes

When dlopen and pthread_create are in libc the variable is
set to "none required", therefore running configure will show
the following errors:

./configure: line 8997: test: too many arguments
./configure: line 8999: test: too many arguments
./configure: line 9003: test: too many arguments
./configure: line 9005: test: =: unary operator expected

gcc/configure also has a similar problem on
gcc_cv_as_mips_explicit_relocs:

./gcc/configure: line 30242: test: =: unary operator expected

ChangeLog:

	* configure.ac: Quote variable result of AC_SEARCH_LIBS.
	* configure: Regenerate.

gcc/ChangeLog:

	* configure.ac: Add missing quotation of variable
	gcc_cv_as_mips_explicit_relocs.
	* configure: Regenerate.

Signed-off-by: Collin Funk <collin.funk1@gmail.com>